on standard boost a r33 gtst is nothing spectacular. i went from 11psi to stock psi when i kept blowing the intercooler pipe off, the power difference was ridiculous. if you cant handle it stock you really need some practice.
just find some open back streets in a quiet area and do a couple of laps. if your worried about losing it while turning or in the wet, gear up before you boost up. you can here your turbo spooling up cant you? go of that, because without boost its just a 2.5L 6cyl.
dont waste money taking power from your car. you will soon get used to the power and what the car will do... and then you want MORE POWWAH!!!