A few weeks back I asked about it in the STX setup thread, got two people suggesting 28psi hot for autox. I've run 32 and all the way up to 37 psi and the tire still feels solid up there, you just won't be maximizing grip.
http://www.ft86club.com/forums/showp...postcount=2717
http://www.ft86club.com/forums/showp...postcount=2720
Track will be different, but I'd suspect their happy place may be fastest <30 psi.
They were pretty fun up at 37 psi though, slippery but predictable.