lvl 2 supension(because of course, lvl's 3 and 4 make the car wheelie to much), lvl 4 drivetrain and engine, lvl 3 nos, lvl 3 forced induction, even lvl 4 brakes, although on the Wii there is no brake in drag. It just helps your traction rating. I just recently started using the corvette just to screw around, and the times are pretty close, mid 6's, and I havent tuned it yet. I'll let you know.