sti all the way. down pipe, cat-back, fmic, ecu mode, and a bov or dv will work wonders. a nice 3" turbo-back exhaust with an ecu mod, like the turboxs utec, will net about 30-35 whp gain alone. sports compact mag did a tech artical on the sti where they used a 3" turbo back and the utec software and made some good smooth power gains. i think it was either the october, november or december issue. the 350z is pretty nice looking and its no joke. there just to damn expensive right now to make them fast. i mean, $6500 for just a turbo kit? maybe in another year or two, the competition for aftermarket support will drop the prices of these s/c and turbo kits.