Well I remember a guy a couple of years ago had to install a 5 point harness to His Saleen S7. This was His DD, and had driven from Maryland to race. But there is a complete rule book on their website. And yes, I plan on entering this year, just for S&G. I wont place, I don't intend to. Maybe after the swap. Also, FI is allowed, but no N2O.
One more thing. Only 160 racers can enter, so Whoever wants to race had better register ASAP