I bought my 05 2.5 RS back in February and have grown to like my daily driver. I am thinking about buying a 05 STI and building it to be a weekend monster. Can anybody tell me who is in the know about building this kind of machine, I need to pick somebodies brain so that I can make the decision as to what I can do and how much it will cost. I would like to know who much HP I can get out of the stock internals. FYI I am looking to kill an M5, can it be done?

 

What year M5? Also do you mean on the track or the strip? If you were do a GT35R Turbo swap into your STI, your looking at 450hp or more.

Turbo swap = Bigger injectors, fuel pump, exhaust plumming, and a good tune.
Do all of these things and you will have one beasty car. Also a new clutch to handle all that power would be needed.

M5's are amazing cars, with that said it may take alot of money to be able to beat one at the track. You will need to tune the suspension, fix the brakes up, and prep the car. It can be done but its not an easy thing to do.

 

Easy

An M5 is no M3 on the track either.

Edit: You're also in the wrong forum. You want the 2.5l turbo section, not the 2.0l.

 

I moved the thread to Car Lounge due to the speculative nature of the question. Look at the Ongoing Projects sub-forum for an idea of how STi owners have modified their cars.

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0==WW==0
"…axles of evil…" - george w. bush

 

This would be a strip car, I am not looking to take anybody on through the curves. Just another thought, has anybody ever set one up to run on Alky. I used to drag race and Alky Injected Turbo bike.

 

You've got a lot to read up on. It's all been done. But if you want to play with an M5 on the drag strip, you really don't need all that much. However, I wouldn't suggest keeping the stock turbo for that amount of power.

 

How much HP can you put through the stock internals and thanks for the help. Do you have any recommended reading material on this subject.

 

Here's an example of spending money wisely...
https://www.i-club.com/forums/bay-area-15/stock-turbo-sti-hits-12-2-%40-112-5-trap-speed-new-record-149342/

The quick, short, and dirty of it...
https://www.i-club.com/forums/showth...tock+block+sti

For good overall usiblity + performance...
https://www.i-club.com/forums/showth...tock+block+sti

Don't take these threads as gospel. Just read them to get a feel for what to expect from doing mild to medium modifications on an STi.