Its been proven that most "body kits" actually decrease aerodynamics. Because the car was wind-tunnel tested in stock form, I would suggest getting a nice lip instead, C-West lip, Greddy lip, OEM lip. Any of those will complement your ride very nicely...what color is it BTW?

If you are set on a body kit make sure its something worthwhile meaning Rando, INGS, C-West any of the Jap kits. But they are way $$$

I would go with a short-ram intake, unless you want to go AEM CAI and have to move your windshield washer resevior bottle, meaning taking off the front bumber as well.

Hope that helps, don't know about the exhaust and such...but tooner is right, look into a turbo kit. Pppsssshhhh!!