The rules regarding frame mods is different at almost every track, except for the handful of tracks around the country that use the rules from our track. Alot of tracks are adopting our rules , we have between 350 to 400 entries a race(usually around 25 in each of the 500 & 750 gas classes). Modified frames have to run in the semi-pro or pro classes.The biggest drawback to the prostock look is the heavy body. But raked frames and extented swingarms work.CBX