Umm, you can get 300-350 easily, without standalone management. However, there aren't a lot of do-it-yourselfers out there building turbo kits for these cars. Most kits from reputable companies will cost $7-10k. But you could get a supercharger for around $5-6k that would put you right at 350-ish. Everybody else feel free to chime in, since I'm no expert on boost. Check some of these companies out for tuning options: www.bmpdesign.com www.turnermotorsport.com www.vacmotorsports.com www.racemarque.com www.sharked.com www.activeauto.com www.bavauto.com www.icsperformance.com
There are more, but these should give you a good start on where to look for performance. I know there are companies out there selling turbo manifolds, but I can't think of them right now. And as for the wheels, Emotions would look badass. Just remember, unless you cover the entire car in it, BMW + Chrome = Ugly... ...usually
Good luck, and welcome man!