I just bought an 06 330i that I plan to autocross. I want to stay in a stock class by SCCA rules, and will run in a street tire class. Currently I am at the bottom end as far as suspension, wheels and tires as the car I bought does not have the sport suspension. So far I have not found what the actual differrences are for the sport suspension so that I know what I can change. I assume the shocks are different and I can do what I want with shocks anyway. Are the springs and sway bars different on the Sport? One of my fellow autocrossers (top guy but not a BMW racer) also told me that I need to go to a large sway bar. Any comments on that? I will probably get a set of 18" rims is 8" in front and 8.5" in rear the max I can do and stay stock? As for tires I had been running the Falken RT615s as they are realtively cheap and stick well. Any other recommendations there? I have most of the winter now to plan for this.