I'd prioritize stopping power first. High-temp brake fluid and upgraded pads. I use this fluid in my car:
http://store.vacmotorsports.com/tota...115-p1790.aspx
Cooling, you'll want to do an FMIC. I have an ETS 5" model and have yet to have a limp mode (though I am N55 engine).
Lastly, tires; Michelin Pilot Super Sport is the king of street tires right now.
Good luck.
P.S. you won't be able to fit M3 dampers on your car without significant modification (read: not worth it).