I don't know....
I think autocross is slow enough, it will be difficult to keep the turbo spooled all the time. When at low RPM's the car feels like a low compression 2.0 litre car. You know, gutless. So, you either have to shift back into first gear, or drop down to low revs in second. Either way.....
I found the 2001 WRX I drove SLOWER than my RS at the bottom end of second gear. This could be interesting.