I autocross my 04 Cobra as much as possible. The real problem is that the nose is so heavy that it just isn't nimble enough on the tight courses to compete. On the positive side everyone loves the way the car and blower sounds going around the track.
Here is a video of crappy but fun run.
YouTube - Supercharged Mustang Cobra Auto-x
Looks like a lot of fun! Don't know that I'd call that autocrossing though. I'd LOVE to drive on something like that regularly. Much more room for our cars to stretch their legs than tight cone courses in parkinglots like most autocross events take place.
Also, I autocrossed my Cobra for several seasons and I don't really think heatsoak is that much of a problem in these type of events. Horsepower is way down on the list of important variables when trying to go fast on an autocross course. The big, heavy nose is a much more limiting factor in my opinion. I'd gladly give up some HP for some grip. :beer: