Nice build and write up. I have been considering building my e92 into an AS car. Currently running my e46 M3 in the failed class of STU (aka lying cheating boost buggies). I ran it in BSP yesterday in TX Region, too not bad.
The point about the e92 and even the e46 being mis-classed is getting easier to make. For 2012 Ford has a Track Pack for the 5.0 Mustang. This pack gives it a Torsen, Brembos, 3.73 diff, and 19" wheels. While the 3.31 and 18" wheels would be better it is the Torsen that will really help. How much different is the 5.0 with the track pack from the e9x M3?
I agree with ESP for the e9x and e46 M3.