Has anything been done to the bottom of it , how much weight have you added and where did you put it , what pipe are you running all these are factors also . A worked over 4763 would be a good starting point
Probably the best idea is to set it up with the can muffler and run it that way in 3 classes if you want to , swapping out a can muffler to a tuned pipe is during a race is not all that fun bc I'm sure the needle setting is gonna change a bit
Rod ,
what gear ratio did you go with ? also i believe 9/32 brass tubing will fit where the teflon liner goes , the pin that holds the drive dog on needs to be replaced as they are pretty weak