there are a lot of threads like this, but to start off you need a boost gauge!
TBE, intake, IC pipes, FMIC, fuel pump, cams, boost controller, and a good tune!
of course not all done in this order, but those are the basics and you can start crushing STI's with ease. this will also depend on your driving skill. if you want the best sleeper look into a cbrd bbk turbo, looks stock but far from it!