Like Monte said under 10 flat you need to have a full cage to be NHRA legal. I know alot of tracks let some of saftey rules slide some on the FAST cars and it may be because they look so stock. I love them and congradulate all of them as its hard work to get them cars to run that hard. I believe the FAST rules say any internal eng mods is legal as long as the eng sounds stock. Who determines what sounds stock ?? And they have to look stock externally. This class reminds me of the great attention the first Pro Stocks cars got in 1970 when everyone loved that class. Good luck to all of them. Ron