Help PLEASE!

I want to change my STi BB which is on a MY02 WRX.

I want to change it for a Firestorm so what will the increase in BHP be (if any)

If i want to increase the BHP further do i then need to change the mid section or is this called the centre section

Whilst posting are there any "cheap" ways to further the performance of the car ie Dawes device (explain this please)

Above all would any of this invalidate the warranty

Cheers

Pete

 

On the warranty bit, I think any of it would invalidate it Although most garages would probably let you off with the backbox...