dyno-max mufflers good / bad?

It's hard to predict the best settings. But jetting up 2, and if that is worse, try down 2 numbers from what you have, should help you "feel" if it helps restore the power you had before. Although the track would be best.

Myron
I went to 36 on the timing and down 5 jet sizes and it's getting close. 40 mph in third gear it will break the M/T ET's loose.