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Modifications on an 03 WRX with 147K miles

5K views 9 replies 7 participants last post by  1round 
#1 ·
Hi there guys, I am the brand new to the forums and am excited to be a member. I just purchased a 2003 WRX, from a single owner,female executive, who kept records of every serviced/scheduled maintenance from 2003 to 2014. The vehicle seems to have never been driven hard and everything is stock and: runs great. My goal is to modify the exhaust;(Up pipes, mid and down), along with some ECU management that is moderate. I would like to obtain around 300 WHP. Do you think attempting this, with a WRX that has 147K miles on it is reasonable? Are there some hard fast rules about modifications after you reach certain high miles?

Thanks again for your help!
 
#3 ·
Welcome to the forums.

A well maintained block with 147k miles should be fine up to 250 WHP but like Epic siad exhaust and a tune are not going to get you to 300. At that point you are playing with fire and Im not sure I woudl want to push a block with 147k that hard.

A definitive list for 300whp doesn't exist but it will definitely take more than just exhaust and a tune. 300whp will most likley require replacing the turbo as well. That can get expensive. If your looking for more power but the 300 number isnt a firm goal there are alot of performance upgrades you can do without breaking the bank.

I say this to everyone, Spend 2,000 miles just driving the car stock. Learn how it handles, what it likes and what it doesnt. Treat it like a new car and give it a break in period until you learn how the machine thinks. When you have driven it for 2 thousand miles then you can decide what you need to change. I grew up on the Brakes>Suspension,>Power model but that's just me.

Just to give you an idea of the common upgrades starting from the front of the car tot eh back

- intake ( highly debated, might not improve HP definitely increases volume)
- turbo inlet ( stock unit creates turbulence )
- EBCS ( to control the extra boost from the new tune )
- STi intercooler (used)
- BPV ( not the psshhtttt, blow off, a bypass valve like the stock unit but capable of holding back more pressure from the new tune )
- Injectors ( may be needed depending on your tune )
- Fuel pump ( may be needed to feed bigger injectors )
- Tubro back exhaust ( choose something with performance CATs so you have a chance of passing smog )

If you get a pro tune with a decent turbo back exhaust, upgraded inter-cooler, and a decent BPV with and good boost controller you can easily hit 240-250 and thats pretty darn fast. If you want more power you can swap the turbo and you will definitly need to swap the injectors and fuel pump. That should put you in the 300 range but at that point you start trading power for reliability.
 
#6 ·
Below is my mod list. I am not sure how (if at all) the 03 differs from the 05 but this will give you an idea on what I have done to get where I am. I could have had my car more aggressively tuned and made 300hp but there are some things I want to do before I go further. I am not saying this is good for your car or that your car would except these parts better or just plain go BOOM.

final @ 282 awhp / 248 tq - on a Mustang Dyno

"Conservative" Tune @ ECS Performance in CT

Mods List

Cobb AP V3
TGV Delete
Perrin Turbo inlet
Perrin Big Maf intake
1000cc ID injectors
200DW fuel pump
Grimmspeed 3 port EBC
Tomioka Billet 20g Turbo
Fast Motorsports Large Top mount intercooler
Catless Ebay 3in turbo back
 
#8 ·
If your looking to get at your 300 mark you might be better off just saving up and building it from scratch.
Would kinda suck to do a bunch of work to the external of the engine only to have something fail on the inside trying to get there.
I wouldn't risk dumping a bunch of money onto a high mileage engine and not do the internals.
At least if you start from the inside/out you know for certain your gonna come close to your mark with a well setup parts list and a pro tune.

But its really up to what your budget is.

If you do start modding keep the forum updated on your progress. :)
 
#9 ·
I would highly recommend not doing that....If you want to make that kind of power then seriously consider A) Saving money for a new motor, B) Save money for a new transmission, C) Save money for misc stuff when things break...Just my advise, but don't take my word for it.
 
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