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2004 RS 2.5L
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10 Posts
Discussion Starter · #1 ·
I currently own a Subaru Impreza RS 2.5L, all stock.
It's at around 83k miles, no issues as of now, and currently under medium usage. Any suggestions for getting a little more power without an engine swap/chopping my gas mileage?

Before anyone says to do some research myself, I have done extensive searching through forums and hearing RS25'ers opinions seems like the best idea. Thanks for responses! :help:
 

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2004 RS 2.5L
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Discussion Starter · #4 ·
Thank you for the link equinox92, @kingsky: my tires are fairly new, maybe 10k on them at most, and the brakes are still quite strong. Thanks for the suggestions.

Question: Superchargers? I looked into/talked to some friends about a supercharger w/dash on/off switch. I know many seem against adding a charger aspect to N/A's but the switch concept interests me
 

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1998 2.5 RS, Brilliant Red
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1,357 Posts
Electric supercharger... no...
adding forced induction to an N/A motor is a tricky affair,
one that will take more than $100 to address, LOL.
Spend the $ on a better flowing exhaust:
header, high flow cat maybe, catback definitely.
Next step would be changing out cams, but you will have to spend a bit more.
Fast, reliable, inexpensive... pick any two you want.
 

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2004 RS 2.5L
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10 Posts
Discussion Starter · #7 · (Edited)
Yea, after reading more into both the budget build thread and thinking more on it, forced induction isn't worth it.
@falcon, not off ebay, friend showed me a shop with several different power options, but they're just too costly.

@dogletnoir, I was reading that changing cats/catback setup doesn't do anything but increase the sound quality, cams I'm not so familiar with and I read about flashing the ECU as well. Any opinions on either of those ideas? I'm tempted to also swap the rear swaybar and get a "grounding kit" but will probably read more into those first

edit: Falcons365 your avatar looks amazing
 

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2004 RS 2.5L
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Discussion Starter · #10 ·
Jdmgary try making your whole post constructive and relevant, because your first sentence is plain douchebag material.

@Joshua. I'm not looking for a neat list, I'm looking for different opinions/discussion. Sorry if "general discussion" is the wrong section for it
 

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Loves Gravel
2001 STM 2.5RS Sedan
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389 Posts
@falcon, not off ebay, friend showed me a shop with several different power options, but they're just too costly.

edit: Falcons365 your avatar looks amazing
Dont Do it, its just a sump pump from a boat. If you must must must do it, go to a marine/ boat shop and pay 1/16 the price. Ask for a "bilge pump." Just don't ask how I know that...

Start with a K&N drop in, UELs, and a catback. Save your pennies and start scrounging Turbo parts from a WRX/ STI, or even for a swap.

...and thanks!
 

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2002 WRB WRX
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420 Posts
You can start with a 20mm rear sway bar to improve the handling of the car, but since you're looking for power mods...

A catback alone will only yield a small power gain because the stock cat is a bottle neck, however, even with the stock cats, it can still improve throttle response and you can find a stock WRX catback for pretty cheap (I got one from a 2006 WRX owner for $80 with only around 4000 miles on it and NO rust). Headers will yield decent gains, but you'd really want a full exhaust with headers+high flow cat+2.25" catback to really maximize the gains. These are the easier bolt-on solutions for more power.

Like someone already mentioned, you can also do cams, but it can be pretty costly to install (around $500 at my local Subaru dealer). I had Delta 1500 cams on 05 RS and it definitely made the car pull harder starting from much lower in the power band and pulled nicely from 2500 rpm to 5000 rpm before it stated to flatten out. Now, combine cams with a full exhaust and it should be a quick little car. If you want to take it even further, you can do intake and a tune (Crawford/iSpeed reflash, ECUTek, and maybe even Open Source, which would be the best option) to maximize the gains from all of your mods.

Doing all of this might not be very cheap (should cost about $1500 with all of the above parts--assuming you buy used parts--plus labor and a final tune) and it'll be a gradual process, but I think that's part of what makes car modding so charming, you can see the step by step transformation of your car as it gets faster every weekend, plus you really learn a lot about your car in the process.
 

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1998 2.5 RS, Brilliant Red
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1,357 Posts
@dogletnoir, I was reading that changing cats/catback setup doesn't do anything but increase the sound quality, cams I'm not so familiar with and I read about flashing the ECU as well. Any opinions on either of those ideas? I'm tempted to also swap the rear swaybar and get a "grounding kit" but will probably read more into those first
General consensus (borne out by my own personal experience) is that a rear swaybar upgrade is one of the first mods you should do; it really made a noticeable difference in the handling of my 1998 RS.
I am running a Blox 22mm rear swaybar with Whiteline heavy duty mounts & endlinks currently. Big change from the 13mm coathanger & stamped steel mounts that came as OEM equipment. If you stay with 20mm or less, you should be able to keep your stock endlinks and mounts, and this mod will cost about $100 or less for a brand new swaybar (less if you find a used one, & that shouldn't be too hard).
Next would be a brake master cylinder brace to help firm up pedal feel a bit
(not sure about consensus, but the brakes in my car felt pretty mushy to me before i added this mod, less so now).
Both of these mods can be performed pretty easily with just a little space, time, effort, and basic tools, and will probably return the most bang for the bucks invested.
I would have mentioned these initially, but you were asking about adding power & i try to stay on-topic...
Happy New Year & good luck with your build !
 

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Modsterdomus
2000 STM RS Sedan 5spd
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7,849 Posts
Any suggestions for getting a little more power without an engine swap/chopping my gas mileage?
More power means more fuel being used. If you increase power you will chop fuel mileage. Every single time.

Now if you would like to just use more of the power you already have that is a different story and much more affordable.
 

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2004 RS 2.5L
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10 Posts
Discussion Starter · #16 ·
@jurzeyfresh, I would definitely like to hear more of that! :)

swaybar: I have a feeling these aren't universal, I was thinking about finding a used stock WRX swaybar? (18mm)

K&N drop: I see a lot of arguments about these filters...

Cams: possible to DIY? I'm going to be doing all work myself and http://www.rs25.com/forums/f105/t96015-diy-delta-camshaft-install.html
looks like a hobby mechanic is not enough :/

exhaust: I would like to do a full exhaust overhaul, probably during the summer as being without a car for a day in the winter makes the walk to work..well...shitty

UEL's: aren't stock 2.5L RS UELs? I'm not looking for a better rumble if thats all the money goes to
 

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1998 2.5 RS, Brilliant Red
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1,357 Posts
18mm rear swaybar from WRX (non-STI) should fit, IIRC.
no comment on K&N filter, never tried one.
cams are a crucial part of your engine, probably best left to someone who knows what they are doing;
expensive, yes, but even more so if not done correctly.
a full exhaust changeover shouldn't take a whole day. I did midpipe/axleback and installed mounts, endlinks and rear swaybar in a friend's driveway with hand tools in only a couple of hours. Of course, if you manage to break a bolt head off, that could slow the process down considerably. Using some WD40 or PB Blaster on the fasteners for a day or two prior to doing the work will probably help.
 

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2002 WRB WRX
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420 Posts
@jurzeyfresh, I would definitely like to hear more of that! :)

swaybar: I have a feeling these aren't universal, I was thinking about finding a used stock WRX swaybar? (18mm)

K&N drop: I see a lot of arguments about these filters...

Cams: possible to DIY? I'm going to be doing all work myself and http://www.rs25.com/forums/f105/t96015-diy-delta-camshaft-install.html
looks like a hobby mechanic is not enough :/

exhaust: I would like to do a full exhaust overhaul, probably during the summer as being without a car for a day in the winter makes the walk to work..well...shitty

UEL's: aren't stock 2.5L RS UELs? I'm not looking for a better rumble if thats all the money goes to
If you can, get a 20 mm sway bar off of an 02 WRX, that's the best bang for the buck since they can be found for about $50, on either here or NASIOC

As for K&N, a lot of people dislike oiled filters and actually, if you want to buy K&N, you might as well buy a Spectre, which is very similar but only costs half as much, I ran one of these for a while. The gains from a high flow panel filter isn't really going to be that noticeable, but I've heard it's around 1-2 HP at the crank.

Cams can be DIY for an experienced hobby mechanic, but I felt that it was too much for me, so I took it to my local Subaru dealer and even then, it took them 2 days to get it done, luckily, they gave me a set quote before they started the job, so I didn't have to pay for 12 hours of labor when the job was finally finished.

If you want power Equal Length headers will give you more power for the buck, but aftermarket UEL or EL headers will yield more power than the stock headers
 

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2004 RS 2.5L
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Discussion Starter · #19 ·
Thanks for the replies everyone, I'll most likely be slapping a wrx swaybar in and possibly getting aftermarket UEL headers/wrx catback!.

Cams again: how much power gain would be seen from swapping these, I looked around and got no concrete ranges? If it's a decent amount I may attempt to do it myself, or ask a mechanic friend to be there so I don't break shit.

tuning: would it be worth to tune a car with 82k miles on it? I heard that it isn't as efficient to do a reflash or anything if it's past like 15k.
 

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2002 WRB WRX
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420 Posts
Thanks for the replies everyone, I'll most likely be slapping a wrx swaybar in and possibly getting aftermarket UEL headers/wrx catback!.

Cams again: how much power gain would be seen from swapping these, I looked around and got no concrete ranges? If it's a decent amount I may attempt to do it myself, or ask a mechanic friend to be there so I don't break shit.

tuning: would it be worth to tune a car with 82k miles on it? I heard that it isn't as efficient to do a reflash or anything if it's past like 15k.
When I got my Delta 1500 cams, I was told by the guys at Delta Cams that they would give roughly a 10% increase in power by itself alone, but if you have the supporting mods, i.e intake+headers+exhaust, you could gain even more power from the cams and even more so after a tune to get the cams and supporting mods working together with your ECU.

As far as tuning goes, it isn't restricted by the mileage of the car, a good tune will actually let the car run better and safer, plus your 04 RS should have a 16-bit ECU which can be reflashed about 1000 times. Also, 82k miles isn't really that much on a subie.
 
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