What's the cheapest, most efficient upgrade to a STi?
i'm talking 15+ at least
i already have a great Intake and im considering a Turbo-back but idk what exactly is for me?
are you talking about the a 1600 or the 2.0l? the easiest should be a branch and free flow system or replacing the chip. if you go to the right place you can get a good set up for a good price.