Tires, shocks and springs, anti-sway bars, exhaust and a chip. I would think thats about all you would need to do. Should be able to do all of that for about $3500 or $4000.
I don't know if I would waist any time on the sound system. Only thing the car really needs is a navigation system. And garmin makes a unit that you can take between cars that is touch screen. Kinda cool.
Good luck.
Tim
visit this page, they've probably got what you're looking for.
http://www.ipdusa.com/products...D=629