Louvers that go on the rear side windows, personally im not a big fan, but oh well... as for exhaust, get a 2.5 inch cat back, high flow cat, and a header and you're golden there, intake needs an open element filter, there is another thread all about it.. since you have a GTS you're golden on wheels, check out the various suspention threads for that, as i dont know much about suspention. if you really wanna get more power you will need to port and polish the head, as well as a bigger cam and bigger valves. exhaust alone is probably worth 15-20 HP, open element filter will give you more high end power, and better flowing head gives you more power all around. the hatch from a supra gives you a good looking spoiler, and a paint job never hurts...