you got a lot of options... theres turbo kits i know for sure, and i'm not sure but i do believe there are procharger systems out there?... cams, forged internals, stroker crank/rods, computers, injectors, intake, exhaust. theres a LOT you can do.
as far as exterior... the simpler the better... tint, lowering, small body kit, maybe a SMALL deck lid spoiler?... stereo is a MUST.