l need some ideas on how to more power in my STl with out going internal and changing turbochargers.also, if l put a turbo back exhaust, will make the turbo noises more louder and noticable? l would also like to know if l put a boost controller in my car, am l able to change boost on the stock turbo, if so what is the maximum boost presure l can go to?
i have a 2003 subaru sti

depending on the year of your STI.. boost controller is a must and the exhaust will make you car louder.. boost controller will probably give you a range from 5-15psi. depending on the model..

l would really reccomend this guy here.. http://vishnutuning.com/ A friend of mine has a WRX that he has put an Apexi cat-back, an up-pipe (primary-catalytic converter delete), a down-pipe (main cat delete), and Vishnu is piggy-back ''Exede'' computer and has run 12.50 is in the quarter-mile..

Is not 300 hp enough?

Richie Rich is right. Shiv at Vishnutuning is one of the best for ECU tuning to an EVO / WRX / STI. l got the Xflash on my EVO & no complaints except that u should do the reflash after you've done the basic bolt ons first.

A TBE will make ur exhaust louder & pending on the state u live in, possibly ur car wo not pass smog anymore, but it is ur most best bet & most basic mod.

As for the boost controller, do not screw with ur boost if u do not know how to tune ur car. You're just asking to blow ur turbo.

Here is a link to the place where l bought all my EVO mods.

http://gruppe-s.com/subaru.htm

Shiv is a penis, also he is in the states. In this guys other post he states he has a 2003 STi which would make it not USDM. If he was in the states, & happened to be in CA I'd highly recommend ed at EQ tuning or Mike at GST motorsports(formerly of Gruppe-S), Shiv is ok if u like superiority complexes & attitude, if u want someone who stands behind their work & does not belittle the customer Shiv is not the man u want to see.

oh & for good deeds, l am at about 550 crank horsepower & it is still not enough.

To the original poster. l answered this question in ur other thread.