With a return to nationals in street mod planned for this year, I will weigh in on this as I get furthur on in the prep update. What I ran in 2005 was basically a Street Prepared car with camshafts, and drilled brake rotors. Updates for this year are: Relocation of ball joints front and rear are being done now, along with bump steer correction. I will be running 18x10 front, and 18x9.5 rear with 285/30/18 tires. Also will be running race seats for the weight savings, but unwilling to give up the A/c for the long drive out to Topeka.
As for aero, not entirely sure there, but will have a splitter and wing. I think there is a huge amount to be gained with center diff control, and plan on upgrading that also. As for power, I only make about 375 to the wheels, and am not sure if more than that is really neccessary for autocross. That will be decided after I run a few events on the new suspension and center diff setup. Oh, and Hoosier A6 for tire choice.
Mark