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Discussion Starter #1
Hey guys I’m new to the forum, but not new to working on cars. I’ve been trying to find information on mods for an NA 2.5L, but most of what I find are people recommending turbos and very pricey mods. I’m looking for mods that I can do myself that won’t be too harsh on the 100,000 mile motor or on the 322,000 mile body. Now I’m not sure if such mods exist, but I thought a good place to start would be here with the experienced community. Any suggestions?
 

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11 wrx & 15 fozzy 2.5i
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Best mods would be a top notch tune up with quality parts. These cars when healthy and running 100% are fun, the 98 revs nicely also. Don’t waste money on an intake, does nothing but noise. But if you’re into noise ok.

I do have a stromüng axleback for sale right now if you want some nice noise tho. Plus website says it makes few extra hp, but can guarantee that if your car isn’t running great now.
 

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2000 Sti Version6
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99 Posts
+1,000 %

Best mod? gasket kit.


simply put, supreme performance requires supreme maintenance.
you don't need a bunch of expensive parts. but be generous with the important stuff.
:blow_money_original
 

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Discussion Starter #4
Thanks! These are the types of answers I was looking for. Also I have a cat back exhaust already, makes some good sound, but not sure about hp increases on it. Would unequal length headers be a good investment? Or would it hinder exhaust scavenging and decrease performance? Also What kind of parts would the performance tuning parts be?
 

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They call me Garrett
98 RBP V4 STi Swapped RS
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4,091 Posts
I had good luck with EQUAL length headers and a 2.5in exhaust on my stock RS engine way back when. There was a small torque bump and everything was just smoother.

I'd shy away from unequal length headers as they are more of a novelty to make your car try to sound like a turbo version.

Past headers/exhaust I really wouldn't recommend dumping time/money into keeping the car naturally aspirated and chasing power. Suspension, steering, etc is fair game though!
 

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'96 OBS
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239 Posts
My favorite mods on my wagon are a beefier rear sway bar and GD WRX brakes (calipers, rotors & pads). Also, some decent tires, while not *cheap*, make a world of difference. If you are dead-set on power, your next step is saving up for either a different engine or some seriously invasive (and expensive) engine work.
 

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Baby❤Daddy
98L Wagon
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27,854 Posts
tires. suspension. brakes. intake & exhaust.

in that order.

i had great fun with my old 98 RS. both on and off road. it had great tires on it when i bought it. did dumb cosmetic mods. bought brakes. bought agx and eibachs. was a blast on every surface possible, pavement, gravel, ice, snow, dirt...you name it, it was awesome.
 

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2001 SRP 2.5RS/RA/SOHC Monster
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As was said, just getting the car to 100% is a huge step. Not only the engine (Plugs, wires, clean up your grounds, some seafoam) but more than anything is suspension. Good struts (KYB AGX!) and replacing the worn out bushings in the suspension make an incredible difference.

I loved the combination of a eBay borla rep header with a stock STI exhaust and K&N drop in filter. I think it did help smooth out the powerband some an opened up the top end just a touch.
 

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1998 RBP Impreza 2.5RS
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My '98 has become what everyone above is describing. I've put in good suspension, better brakes and great tires while leaving the engine stock. It still isn't very quick in a straight line, but it's a riot in the corners. I beat the piss out of it on the street and I've taken it to two track days and it's still kicking. All it's taken is maintenance with oem parts.
 

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I also have a '98 RS that I've turned into a weekend track car. It's still naturally aspirated and you could say it has been more reliable than the turbo models. Every part on the car, down to the nuts and washers are all OEM, besides any parts I added onto the car.

The only thing I've done is welded the rear differential and the car is gutted, still working on some PITA sound deadening material. This is, I plan on stiffening the chassis.
 

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Has NA 2.5L, Any suggestions?
This is the infamous EJ25D - Internal Head Gasket blowing machine.

Do keep your coolant fresh and oil changes frequent.

Do Watch the temp gauge if it EVER goes above that "just below half-way" point, the HG is likely about to give it up.

Do STOP driving if it even looks like it's overheating, tow it home and fix it immediately. Rod bearings hate overheating and coolant...rods get 'ejected'.

Do Keep your valves adjusted (nasty shims) or you'll end up w/a burnt valve, and @ 100K your timing belt is due.

Do clean your MAF - w/the proper spray.

Do Not get a K&N - oily filter isn't good for the MAF - and you already have a CAI, so as stated above - no intake needed- unless you're into the noise.

@ $100 x 4 for the cams, Delta has options....

Do not let anyone else drive your car, either.
 

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I noticed a big difference when I went from 2.2 to 2.5. Felt a difference in torque when I changed the header, exhaust, and intake manifold. I installed all the parts together so I don’t know which three made the biggest difference
 

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2001 gm6
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103 Posts
Best bang for buck would be maintenance, suspension, braking, good tires. I recently did rear sway bar and that made a huge difference. Before that I was used to the so disappointing understeer. Rsb made the car fun to turn. Kyb ag with eibachs were also a good model for me.
 
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