Having an RS is a good starting point as it comes with a 2.5 liter engine and a decent suspension out of the box (98 and up). A 2.2 L from 97-01 will do well too and are more common. 2.2 LX models from earlier the 1997 are good too. Outback Sports are essentially Impreza wagons and are not to be confused with Legacy Outbacks. Legacys are acceptable too, but they generally weigh more. This guide is mainly for the GC/GD style Impreza, but many of the methods can be used for any other NA Subaru. Everything else is generally the same.
EJ18 (110HP, mostly reliable)
EJ22 (135-142HP, bulletproof)
EJ25 (165-170HP, reliablity varies)
Anything with a 1.8 probably isn't going to cut it, but I find a 2.2 is a good starting point. A swap to a 2.5 NA motor is probably even out of the question for many of you using this guide. Also, for the transmission, get what you want, MT (manual) or AT (automatic). It's a daily driver, AT is ok, don't let others tell you otherwise of that's what you need/want. A manual is probably more fun, but if you don't want to be shifting all the time on the way to work or it's just not your style, don't get one. Consider the pros and cons of both. 4EAT Subarus (4-speed electronic automatic transmission) actually have the most advanced AWD systems, running 90% power to the front and 10% to the rear under normal driving conditions. When wheel slippage is detected, power shifts to 50/50, or the wheels that are slipping.
Also take note of the gear shifter on the automatics. Traditional 'D' will allow the car to shift like any other automatic, attempting to reach 4th as quick as it can. '3' is the gear which many people don't understand. It allows the car to shift through gears 1, 2, and 3, but not into 4th. This allows for better pickup on highways and better power delivery on backroads. Selecting '2' is a special gear to be used in winter when you don't want the car shifting. You can also use it for declining down steep hills. '1' is basically the same, just a lower gear. When in '1' and '2', the car will not downshift or up shift into any other gear.
You can read more about the 4EAT here:
4EAT Basic Information FAQ
Ok, from a reliability standpoint, the EJ25 is the least reliable of all three NA EJ series engines. They suffer from more headgasket failures mainly. After about 120k, you're pretty much prone to something happening. If it lasts past 130-140k, you're on borrowed time. Headgasket replacements are about $1000 so from the dealer, so such an expense would be a major one. Look to see if this has been done before. The EJ18/22 tend to not suffer from this issue until about 200k+ and even then, it's just a maybe. Let's face it, the body will probably rust out before then.
Once you have car, remember to inflate the tires properly. Use about 2-3 PSI higher in the front than back. Many people overlook this.
It's free... you can't get any cheaper than that!
If you want a quick guide on things to look for when purchasing a used Subaru, refer to this guide:
Used Subaru Buyer's Guide
Estimated cost: $1000-8000, given condition, mileage, trim level, etc.
Planning: A Message to All
What do you want to do with it? Do you want your L to look like an RS? If so, that won't really be covered in this guide, but it's something to consider. Do you want JDM tails? That's going to cost a good bit in your budget. Is there rust to fix? You need to fix that ASAP before it eats your car alive. You even need to consider if you'll be running some auto-x and need to stick to the modification rules there. You’re probably going to do something with your corner lights and side markers too. Before you install your sway bars or strut bar brackets, you may want to paint them a color like red/blue/pink for some added personal effect, just don't go overboard or too flashly. These are all personal, visual effects that will not be covered in this guide. They probably should be tackled after you upgrade your tires and swaybar.
Getting power from your NA engine is not the most cost efficient thing and remember, this is only your daily driver and not a track car. Spend your money wisely. You will be very pleased with suspension mods that you can really feel. Things like intakes and exhausts will not significantly increase horsepower - you will probably not even feel a big difference.
Word of warning... read, research, reread, reresearch. Do a mod once and do it right. Nothing sucks more than buying a new mod and finding
it doesn't fit or do what you wanted it to!
Estimated Cost: Free!
Maintenance: First Things First
Before jumping into the whole modding scene, you need to have all your maintenance up to date. Some things should just be changed because they’re so cheap. Let’s get started.
Spark plugs. Let’s face it, you can get a set of four spark plugs for $8-15, sometimes up to $30 or so for those fancy ones. Subaru specifically calls for NGK V-Powers, which is what I suggest that all NA owners use. Turbo models can use the same, but things get a little more complicated there with tuning, heat ranges, and things like that. Stick with the NGK V-Powers or even standards, using the correct heat range. I’ve seen some EJ25 use a 5 heat range and EJ22 use a 6 heat range. Check your manual for this. The 5 or 6 will be in the part number.
Generally, colder plugs mean better performance. It’s not to say you’ll gain X amount of HP, but you’ll have a more efficient spark, leading to better fuel economy and just generally smoother operation. For the price, these should be changed every 15k and immediately when you get a used car. Copper spark plugs (standard and V-Powered for the NGKs) last about 15k and the Iridium ones tend to last 30k or longer. I think it's best to use the copper ones since they say copper conducts better and it's always good to check them often.
Heat range diagram:
Changing them however, is far from a Honda, or other inline four. The boxer engine has the spark plugs on either side of the block at odd angles. Estimated time is not 15-20 minutes like usual. This is about an hour job. Don’t rush this. Also, make sure to torque them to the correct specs (about 15ft/lbs I believe) and it’s always a good idea to use some anti-seize on them to get them out easier next time.
Next, if this is a new car to you (used), change the oil. Subaru OEM oil filters are perfectly acceptable for most people. Read more about them in my review here: Subaru OEM Oil Filter Review (Blue)
Next, check the tranny and front diff fluid. The dipsticks for these are located on the driver and passenger side of the transmission area behind the engine respectively. The color of this fluid should be red. Pink is ok, but if it is gray, you’re probably experiencing some shifting problems and could be doing harm to your transmission. Keep it at least pink. Fluid usually lasts about 15k miles and should be changed with Subaru fluid in my opinion.
The fuel filter is located over by the fuse box in the engine bay and looks like a black canister with two lines attached to it. This should be changed every 30k or so. It’s a $40 ish part, so I’d only change it if your gas mileage is crappy.. or if you know it has about 30k on that filter.
Also check your axle boots. The one on the passenger side in the front usually goes a lot more than the others since it’s near the exhaust and heats up a lot. It’s always good to spray silicone on them to keep them flexible.
Estmated cost: it really depends what you do. As low as $15, as much as $150ish.
Swaybars: Best Bang For Your Buck!
Before you start with anything, get a rear sway bar to upgrade your 13mm bar with. This is to drastically reduce body roll and understeer with an AWD vehicle and is the best suspension mod for the money you can do. This will be a huge difference, even with the stock wheels and tires. If you do not have a stock 13mm bar installed on your car, then you will have to purchase brackets to use the bar. You will want to go 17mm or 18mm if you are sticking with your stock L suspension or 20mm if you are sticking with your RS suspension. If you plan on getting RS springs for your L (or aftermarket springs/struts), it is possible to go with the 20mm now and use it until you get the new springs. If you have a GD RS or 2.5i (02+ models), I'd suggest 20mm be your starting point. These vehicles are larger and weigh more, hence their body roll is more pronounced. The only model a 20mm might be a little too big on is a L with stock suspension. Legacies use different swaybars than Imprezas and are much harder to find.
The best thing about swaybars is that they do not affect the ride quality much. With springs/strut/coilovers, you make the entire car ride harsher, but stiffer. Major gains can be had from replacing those suspension components, but the tradeoff is the ride quality. The tradeoff rule does not apply to swaybars.
Endlinks, which go on the end of the bar, are not necessary and you won't feel any difference at all with them over the stock plastic ones until your bar is more than 20mm. Therefore, I'm listing endlinks as optional. As for the bar, you are getting that used too. 17mm are common and came on the WRX. The 20mm came on the 02 or 03 for a short period of time and they are a bit harder to find and may be a few bucks more. An 18mm bar is very hard to come by as they are not plentiful and did not come on any models that I know of. You can purchase an 18mm bar off SubaruGenuineParts.com for around $80, but I'd highly suggest looking for a used one.
For more info on stock swaybar sizes, refer to these threads:
Stock RSB and FSB Sizes
Compiling Stock Front Sway bar/RSB size chart
Compiling Stock Front Sway bar/RSB size chart v2
Estimated Cost: $50 used
Wheels/Tires: Keep It Glued to the Road
You might need new tires at this point, so let’s evaluate your wheel situation. If you have an RS, your set with alloy wheels already, so keep your stockers and possibly paint them to your liking. These wheels are 7" wide and are light. If you want lighter wheels to yield better power and acceleration, you're going to have to pay up big time. They're already really light to begin with. If you still have the stock steelies with hubcaps, those need to go. They look like poo! Look around for used stock wheels in your area here or on NASIOC. You will probably have more luck on NASIOC with 02-04 WRX wheels because they are common and cheaper than RS wheels (about $200-250 is the going price). You are looking for 16 or 17 inch wheels. Most all Subaru wheels are interchangeable except for STi wheels which are out of your budget anyways. You need a 5x100 bolt pattern.
If you must get aftermarket wheels, make absolutely sure the offset is within the correct limits. Stock Subaru wheels are around +50. Something that’s +35 is going to have an effect on wheel bearing wear. Also if you plan on lowering your car via springs or coilovers, offset can be the difference if your tries will rub or not.
Wrap your new wheels in a good tire (absolutely don’t skimp here!) for your climate using TireRack's reviews. Mostly you will be looking for a good all season tire depending on where you live, assuming you do not have the budget for two sets of wheels (summer and winter). All season tires are the jack of all trades and are acceptable at everything, but not 'good' at anything. Again, here's the tradeoff theory coming to play again.
If at all possible, get two sets of wheels, one for winter and one for summer. Let's say you have steelies. Buy some RS or WRX wheels for summer and wrap them in summer tires. Use your steelies for winter because number one, they're badass, and number two, they're cheap. How cheap? Well since you already have them, consider them free.
As far as tire sizes, stick to mostly stock. For winter ties, stay with 205 widths as they cut through snow well, but also allow for a good amount of tire to be on the road when it's not snowing. For summer tires, go with 205 or 215. The wider the tire, the more rubber is on the ground and the greater amount of friction you have with the road. More friction increases cornering and braking aspects positively, but also slightly decreases gas mileage. Get a sidewall that keeps the total circumference of the tire as close to stock as possible, but edge on slightly larger if it comes to it.
Remember that your tires are the only thing keeping you in contact with the road, so make sure you buy a good quality tire for your driving situations. Tires affect cornering limits, braking limits, and to some extent acceleration limits, depending on weather. Do not skimp on them! I will touch on more about the braking aspects of tires in the brakes section.
Estimated Cost: $200-300 for Subaru wheels, $350-500 for tires
Strut Bars: They're Debatable
Strut bars connect the strut towers and reduce body flex. When the car is pushed hard, or even when you just go over bumps, the body flexes. Strut bars help keep this flexing to a minimum and are the cheapest bracing available. You are going to want to get the Ebay strut bars. They are worth the $50 or so no matter what anyone else will tell you. You will feel a slight difference and will make your chassis firmer, but don't expect wonders. Paired with the rear sway bar, you will have a good suspension start already. Remember GC/GF Imprezas (93-01) and GD Imprezas (02-07) are totally different chassis and use different strut bars.
Get the one for your vehicle as the other will not work at all. Wagons will benefit greatly from rear strut bars as you can clearly see there is a large opening in the passenger and cargo area. In the coupe/sedan, this is a bit sturdier with the location and design of the trunk. I would still recommend the rear bar for the coupe/sedan.
Estimated Cost: $50 for both front and rear
Brakes: An Interesting Philosophy
Brakes are important. Really important. But, here's the the thing. Production cars come with braking systems that are completely capable of locking up the front tires even with sticky summer tires on them. So theoretically, if you want to increase braking performance, get stickier tires. This goes for summer tires, as well as winter tires. You can have a $2000+ big brake kit with summer tires and slam that on in the snow and I can guarantee that someone with 1 pot stockers and rear drums, paired with winter tires will stop sooner than you. Both
braking systems will lock up the brakes, leaving all the braking duty to the tires.
Given that philosophy, keep your stock brakes, but there are some cost effective brake related upgrades. First, understand that slotted and cross drilled rotors are mainly for looks. They can even crack or break, which is very bad. Keep your stock rotors or get replacements if you need them. It's worth the extra cost to get the premium ones that don't rust and are sometimes painted, just for visual effects. You'll thank yourself.
Second, pads wear out. When they do, it's time to upgrade. Remember what I said earlier... stock brakes lock up the wheels just fine. Why upgrade now? Braking is all about feel and modulation of the pedal. Pads with better friction 'grab' better initially, giving you a better brake feel. Typically these are about double the cost of stock pads, but are worth it when they need replacing. If you do any brake upgrades at all, get new pads. Hawk HP and HP+ are two common upgrades and cost about $100 per set.
About 90% of your hard braking on concentrated up front, so if you have rear drums, just keep them. Upgrade the front pads later when they need replaced. Under normal everyday braking, the rears are actually used more, but this doesn't really matter from a performance standpoint.
I also recommend a brake fluid flush about every year or two to keep the brake pedal feeling good. This can be done in your garage at home for about $15 for fluid and the know-how or about $80 at a shop. If you don't know what you're doing, take it to a shop... it's your brakes for God's sake! Just roll with standard DOT3 fluid. Dot4 fluid is only an upgrade if you are tracking the car and really heating up the brake fluid, which you won't be. Autocross doesn't count in this respect.
Recently master cylinder braces have come about and cost about $100. These brace the master cylinder (who could figure?) and hold it in place under hard braking. The master cylinder presses on the firewall, which can flex over time. This creates a mushy pedal feel feeling too. This fixes that problem. Because this is an easy install, much easier than installing stainless lines, I'd recommend looking into it. Stainless brake lines will also help with that mushy pedal feeling Subarus are known for, but are a bitch to install. They also cost $100.
If you want to read more about brakes, read here:
Upgrading to High-Performance Brakes
Estimated Cost: $0, or $100 to upgrade when replacements are needed
Grounding Kits: Commonly Overlooked
You are going to want to get a grounding kit for around $30. This will help smooth things out on the power band and get rid of the sluggishness/bogging in first gear in parking lots. I’ve even heard it eliminates the hesitation around 3-4K when accelerating. Paranoid Fabrications (CamoToy.com) have these kits starting at $30 and up. You can also get these on eBay, but I am not sure of the quality.
Usually eBay is ok for things like this, but PF is a good vender and his products are priced well. The kits are also made to the exact lengths you will need for your EJ engine. The kits are additional wiring to go along with the stock wiring and are not a replacement - they are an addition. One thing I do not like about PF’s kit (even though I do own one) is that it’s a daisy chain setup, meaning all the wires are attached to each other. The eBay ones radiate out from a central point, which is probably better for grounding. PF also sells another kit called the Big Three which will replace your stock grounds. This would be a nice upgrade too, but I think most people would be just fine with the additional wires of the basic kit.
Paranoid Fabrications Grounding Kits
Estimated Cost: $30
Lighting: Driving at Night
Let's face it, stock bulbs are yellow-ish and how low power outputs. "OMG my buddy has HIDs and they're awesome!"... No. They're not. They're probably not installed correctly with projector housing lenses and are blinding other drivers on the road making it unsafe for themselves and others. A good HID kit including bulbs and ballasts are going to run you $100 and the projector lenses are going to run you $200+ if done right and require a good amount of knowledge. Skip this route.
Get upgraded replacement bulbs. Don't get those blue tinted eBay ones. They burn too hot and can damage your wiring harness and then you'll be SOL. Don't get anything tinted. Tint on the bulb or housing only diminishes light output. A good bulb I can recommend is something like the Nightbreaker Plus. They fit right into stock housing and are an upgrade from stock. The low beams are whiter, but are not blinding to other drivers. The high beams have a lot of light output and are great for a daily driver. I'd also not suggest going to your local
autoparts store and asking them for their brightest bulbs. They'll tell you Sylvania Silverstars are, which probably don't even produce that much more light than stock. You'll need to order the bulbs you want online.
Estimated Cost: $30
Spring & Strut Combos: Transforming the Car
Now, you’re well on your way to an enjoyable car. Your car should be handling well with the rear swaybar and strut bars already, but with older cars the struts can be leaking and may need to be replaced. Let's understand one thing to start, there are spring and strut combos and there are coilovers, which are essentially fully adjustable spring and strut combos that allow you to choose a ride height of your choice and also change the dampening settings (harshness). Coilovers are expensive and spring/strut combos are much more affordable and suitable for a road car in my opinion. KYB GR2 struts are about 15% stiffer than stock and will be a good upgrade for any blown struts. KYB AGX offer some adjustablity dampening-wise, but are not close to the adjustability of coilovers. You can not adjust ride height with spring strut combos.
However, when you choose a suitable spring for the stut you choose, you are essentially choosing the ride height, hoever this can't be changed later like with coilovers. Unless you get new springs of course. You may be thinking about lowering the car for visual effects or for handling. You will enjoy this, but remember you don't want to go too low or you won't be able to get around town. Also remember stiffer/harder is not always better - your car should be able to absorb the bumps and dips in the road, yet still feel stable. There are tons and tons of springs to choose from all with different ride heights and spring rates. Choose one you like. I can offer one word of advice... don't get S-Techs!
This will be a major expense, but it's worth it for sure. It totally transforms the cornering characteristics of the car and also helps in braking a little too by stabilizing everything. It's highly suggested you upgrade these components, but only after the above ones.
Estimated Cost: $300 for just struts, $200 for aftermarket springs, $500 total
Exhausts: Make it rumble!
Now you are ready for some power upgrades. First will be your exhaust. You'll mainly want this for sound and enjoyment, so get something you like the sound of and stay away from Ebay. There are four main parts of a Subaru's exhaust. An axleback is the muffler and the tubing that connects it to the next piece, the midpipe. The midpipe is a simple pipe that runs most of the length of the car to the catalytic converter or simply 'cat'. The cat connects to the headers, which connects to the engine. The term 'catback' as commonly used by tuners is the axleback and midpipe, usually in a complete package.
You'll be looking for an axleback only, most likely used. A lot of 'exhausts' from Ebay are just oversized mufflers that are loud. These can be found on NASIOC or RS25. This will change the sound drastically. A midpipe or center pipe will not do much, so keep your stock one unless it's ready to fall off from rust. As for piping size, any size for the axleback is acceptable (2.25-3"). Turbo models such as the WRX have 3" piping and products specifically for the RS have 2.25-2.5" piping. If you plan on replacing your midpipe, you need to keep it at 2.25" for the flow of air to have the best velocity exiting the system. Going bigger is not always better. To start researching these, I suggest getting on YouTube and typing in "subaru exhuast". Then keep clicking and going to related videos. When you find a few brands you like, search for them in the classifieds. If you are really picky or can't make up your mind, go to a meet in your area and ask around.
Listen to other's exhausts in person and see exactly how they sound.
Threads with videos of exhaust setups:
The Official CAI/Exhaust Thread for N/A Scoobies
Official "Which Exhaust Should I Get" Thread
Any aftermarket axleback meant for an RS or WRX will work, but if you get one from a WRX, you will need to turn the flange via welding at a shop. It's something to consider, but does not cost that much. Using one from a WRX will also give you a wide variety of sounds to choose from. Another cost efficient choice for those of you wanting to change the look of your exhaust, but still keep things quiet is to get a WRX or STi stock axleback. WRX and STi axlebacks bolt right up to the 06-07 2.5is, but all other models will need to have the flange rotated and the pipe lengthened a little. Again, this all can be done at an exhaust shop for a reasonable price, just as with the aftermarket axlebacks. Although remember, if something happens to your midpipe/cats/header such as an exhast leak or rust, it is cost efficient to replace these with aftermarket parts rather than new OEM parts from the dealer.
The next part in line is the cat. You will not want to change this. There are 'high flow cats' available and even track pipes (a track pipe totally eliminates the cat and just connects it with a tube). Here is a graph on an '05 RS showing four dyno runs, two with a stock cat and two with a track pipe.
You tell me which ones are with the stock cat and which ones are with the $200+ track pipe. You can't, so don't waste your money. Next are headers. If you have an RS, stock headers are unequal length (UEL), which is one of the reasons Subarus sound like they do. Borla UEL replica headers from Ebay will amplify your "boxer rumble", but are also another $200. These are the cheapest aftermarket headers around. The main thing to remember with headers is if your dual port or single port. The Ebay ones are dual, as are the real aftermarket Borlas (real Borlas are around $500). There are not many choices for the single port folk. Borla made single port ones years ago, but they are very hard to find. If you have single ports, you’re a bit out of luck with headers.
If you do have a 2.5i with equal length headers, your axleback may end up sounding more like a Honda. It will not totally sound like a Honda due to the actual engine configuration. To fix this, you will need to get unequal length headers.
There are also equal length (EL) headers available too, which will net you marginally higher power gains, but the Subaru rumble will be severely effected. This is how much airflow you get with UEL vs. EL:
Not enough to justify the cost. In my opinion, get an axleback for the sound and maybe the replica headers if you have an extra $200 laying around. You'll LOVE the sound, it just won't net you a ton of power.
Estimated Cost: $200 for an axleback for just sound, $300-1000 for a full system with minimal power gains
Intakes: Let the Debate Begin
You may have been wonder when we're going to talk about intakes. First, do you have a MAP or MAF car? Pre-99 models were MAF (when dealing with the 93-01 Impreza), as 1999 was the crossover year. Some GD models are MAF now too, so just check to see if you have one. This is a small square box (as looking from above) right next to the airbox. If you don't see this, then chances are you don't have one and your car is MAP. These are costly to replace.
If you do not plan on upgrading your intake and your air filter needs replacing, either get another paper filter or get some type of dryflow filter which does not require oil. Do not get a K&N filter. You will not gain anything from adding a K&N filter, they are expensive, and let in more dirt partials. Modern engines have ECUs that compensate for dirty filters, but having one that's free flowing is better than a half-blocked one. Your filter should be changed or cleaned every other oil change.
Aftermarket intakes are a touchy subject with Subarus, but I will present the facts and you can choose what is best for you. A SRI (short ram intake) replaces the stock piping and puts a cone filter at the end where the airbox is. With MAF cars, this could mess with your air to
fuel ratio and cause you bogging and problems, not to mention they are loud and this is something you don't want with a daily driver. Also, many of the oiled cone filters can grease up for MAF sensor, leading to costly replacements. Also note that you are sucking hot air in from near the engine, which isn't great for combustion. Your MAF sensor will go right before the cone filter if you have one.
On the other hand, a CAI (cold air intake) extends down into the fenderwall and sucks cold air from the outside. The cold air is better for combustion. Since they sit low to the ground, they may suck up water and cause hydrolock to your motor, although this is rare and only happens if you’re driving through rivers. You generally only use a CAI on a MAP sensor car though. I'm sure it's possible to make a CAI with a MAF, but generally most CAIs that I've seen do not have a place for the sensor.
Generally, SRIs and CAIs work effectively with MAP based cars, as they are essentially a tube with a filter on the end. You can see a small improvement in power, especially higher in the RPM range. Many people have had losses in low end power and torque, or bogging off the line.
Subaru intakes are designed for low end torque and power. If you change the bends, resonators, accordion tubes, or whatever, you’re going to mess up the intended flow. To compensate for this, you need to be tuned to tell the computer what you changed (to keep it in simple terms). With SRI and CAI, after you are tuned, you can see decent gains too and not much loss of low end power.
Also remember price too. Injen CAIs run about $250. AEM and similar SRIs go for about $100. You can get these new for about half the price; just remember to have a clean filter on the end. If you search Ebay, you'll find many intakes for all kinds of cars. Basically, 95% of these are crap. You can use the piping, which will probably need modifying and add your choice of cone filter at the end. You will need this piping for the hybrid intake and will need to chop it up to get it to fit in place of the stock tubing. There are also various types of DIY (do it yourself) intakes that utilize PVC piping with a filter at the end.
More recently, people have been modifying their stock intake systems. They claim you can gain most of the power you would from a SRI/CAI, without the low end loss. You can find the thread stickied in the NA section of NASIOC, or click here:
If you have a stock intake with the filter in the ‘torque’ box above the throttle body in the engine bay, get the Accord intake pipe from ebay and you’re all set. It’s really the best and absolute cheapest intake ever. This is or MAP versions only. It’s only $20 and provides good gains in the high end without touching the already great low end power.
The stock intake is specifically engineered to produce low end torque and be used with the stock ECU. Once you modify the intake, you change how the air enters the throttle body and intake manifold. Take for example this thread (http://<br />
), post number 14. Since installing the hybrid intake, the person has noticed the adverse effect of losing a quart of oil. He could be losing oil for another reason, but I would highly doubt that if it's only an '08.
He had been using it as a SRI, which cause his car to run lean and is probably the cause of burning oil. What I'm getting at is that modifying your intake can very well cause adverse effects, so just be careful and read up!
The main thread talking about hybrid intakes on NASIOC is a great source of information. Basically the MAF gets messed up even if you remove the snorkus in you fender, as seen by this chart:
If you install a SRI or CAI, you eliminate the snorkus, so you have this problem. My honest and best suggestion is to leave your intake stock or do the hybrid intake. With the hybrid, you’re only modifying the piping after the MAF, so the MAF reads correctly. You will only run a tiny bit lean, which theoretically will increase gas mileage and will not harm the engine. You will not throw any check engine lights either, which can be caused by SRI/CAI.
Surprisingly I did find this:
This is a graph of someone who road dynoed their hybrid. They apparently lost power. I don’t know what to say, but it is a road dyno, not a professional dyno. Try the hybrid and see what results you get. Each model is different and reacts different to intake changes.
*Note: It is always a good idea to reset your ECU by disconnecting the battery after adding any mods pertaining to the engine/exhaust/intake.
This will allow the ECU to learn how its new component effects the entire setup. You might feel a very small gain with your intake or slightly better gas mileage after the first fillup.
Estimated Cost: $0, or $30 for a Ganzflow replica or hybrid
Modification to Avoid: Don't Do These!
There's one thing about being a DIY person and another about being unsafely cheap. If you're looking to lower your car, don't cut your springs. It negatively affects handling and is unsafe. Replace anything that needs replaced when the times comes and don't mess with your brakes if you don't know what you're doing, especially the hydraulics.
There are some basic things I won't waste my money on. First up is pulleys. If you reduce the amount of effort needed on the drivetrain, you'll essentially get more power to the wheels. All aftermarket pulleys for EJ engines will work on any other EJ engine. To be cost effective, the crank pulley is the one that I would consider replacing to a lightweight version and keep the others stock. It does not matter if you have an automatic or manual transmission with these, either will work. Do not get an underdrive pulley, there have been problems with these in conjunction with the others. Get a lightweight one, at stock size. Your car will rev faster and be more enjoyable, not to mention a slight possible increase in gas mileage. You can get a set of all three pulleys (crank, alternator, A/C), but this will cost more than just the crank. People have reported to have problems with lightweight pulleys paired with lightweight flywheels. The combination appears to be just too light for the ECU to handle and you may have problems idling. Due to these negative effects and the difficulty of installation, I'd just avoid them all together. The gains aren't worth it.
Two, just restating the HID kits I touched on above. Go with bulbs instead. I feel they're a waste of money really.
Three, again already stated, fancy brake rotors. Sure they look nice and cost a pretty penny, but they're not worth it.
Four, aftermarket wheels. Ok, this is debatable. Wheels cost a lot, especially good name brand ones. I just simply think Subaru wheels get the job done and look fine too. Paint them if you want another color, it'll cost about $30 or so. I just don't think they're worth the $500+ you'll be spending if you can get WRX wheels for $200. There's nothing really wrong with them, but I can't justify the cost.
And finally, any 'racing chips' and such... basically anything with the name 'chip' in it. They're not real. Tuning programs and software are real, but expensive and not needed for the mods here. Read more about these things here: Racing Chips? e-Bay Chips For N/A?
Now you have a decent daily driver and possibly auto-x car. If your follow this guide, it should generally guide you in the steps and help you begin. Building a nice car is not as hard and as costly as many make it out to be if done right. You can roughly estimate it will take you about $1000 or so to do all the upgrades listed here. Even 2.2 L models can be turned into decent cars. Now, I know many people may disagree with things said here, but this is to guide those who have no idea where to begin or how to spend their money. Also, this is for people who can't or don't want to spend all their money on their car.
Also, remember, when modifying anything dealing with the engine (intakes, exhausts, pulleys, etc.) you might get a "check engine light", more commonly referred to as a CEL. You can even get them randomly if any of your sensors stop working for any reason or things break. Don't freak! Get the code pulled at your local Autozone for free and match the code with the problem on this thread so you know what to fix:
List of All Subaru CEL Codes
*If there are any problems with this guide or wrong info, please post up. I don't want to mislead anyone. Discuss things about it too, we're here to learn and give opinions. I will periodically update this as products and opinions change. I may also add pictures or links sometime too.