I went to a WORCS race last year to watch a friend, before i got my 400. The race was at a track that they dont have in the series this year which is the one i live by(

). I dont know what you mean by "grand prix", but if i can remeber it is 60 minutes as many laps as you can get in on an off-road type course(hense the name World off road championship series), not too many jumps. They get an alright turnout, when i when they had about...8-10 classes of 6-8 riders including the pro class. They have one class go, then they let the next class go sixty seconds later. You need a 45 dollar deposit for the transmitter they give you to track your lap times, and then i think 65 to race. Hope this helps, good luck.