I am running the original 790 with thunderbike pipes and freak, I have got the TPUSA 904 kit with 813 cams,Fast Fred modified head with bored carbs and intakes that I have to install yet and I'm going to run the stock 16T sprocket. These are not big torque engines and enjoy the rpm's. In my opinion the original 16T speedmaster sprockect is the way to go.
