horse power

Im kinda a newbie at this and want to buy a turbo back exhaust. I have a 2007 wrx. i kinda want something cheaper but am willing to spend some penny in some time. what are the benifits of some and what one to try and avoid.

I have just purchased a new 2010 wrx and well i want to do something to it but... the problem is is i still want the warranty. i wanna get a few more horses out of the car but i really want your opinion and your knowledge on things I can do to the car withought asking the dealer or with asking...

i have a 2004 sti i would like to know the first steps to get to 400hp. currently i have a TBE and still has stock up pipe. Does anyone know if the up pipe is catless on a 2004 sti? first i will get a Cobb AP to run stage 2 but would like a better direction from there i just want the next step...