For ASP and autocross in general, the biggest bang for your buck is going to be fitting as much tire under the car as possible. My Stock-class car fits the 295/30-18 and 315/30-18 Hoosier A6 under it on the stock wheel widths, so that's your starting point. Several people have used 285/30-18 A6's square on 18x10's if you want to do something that's proven to work, but this car needs more rear tire than that on an autocross course. If I were building a full-tilt ASP car I'd find a way to get the 315/30-18 Hoosier to fit up front, which would probably mean custom 18x10.5's and some new fenders, and the 335/30-18 in the rear on 11.5's would fit with some small fender modifications, but you're probably not interested in going that far. You might also consider the BFG R1-S, they are about $200 cheaper per set than the Hoosiers and offer very similar performance, and the 285/30-18's are wider than the 295 Hoosier which might be a good compromise if you want to run square.
The next place to look is a GOOD set of coilovers with some much stiffer springs. I'd look past KW to a Motion Control Suspension, JRZ, or Moton setup if it were my money. There's no reason to bother with an intake or headers on this car, they make next to no power and save no weight either, so use the money you save on not pointlessly modifying the engine in the suspension. Key here will be maintaining tire clearance, because tire/weight is arguably the most important thing in autocross after thrust/weight. Many coilover setups eat into tire clearance in the front with the adjustable spring perch. Motion Control for sure can make a setup that will actually improve tire clearance to the strut, not sure about anybody else. I don't know anything about the KW Clubsport so I can't help you there.
Next, I'd focus on getting weight down. Seats, a lightweight battery, and the wheels you buy should be worth in the neighborhood of 150lbs, and more can be lost in the exhaust as the Borla system and stock midpipe both weigh quite a bit compared to some of the race parts out there
If you're getting the Evolve tune I would keep the stock redline rather than opt for the increased rev limiter, 70mph is plenty and you'll be banging against the limiter enough that I wouldn't want to add any extra stress. I'm usually on the limiter in 2nd at least once per event even on tighter courses
Last edited by Richbot; 08-30-2012 at 12:21 PM.