I switched from Mobil 1 racing 2t motorcycle oil to Redline two stroke racing oil last year and I can tell a difference, all of my gassers run better.
Does your ignition have a timing feature? Mine is set for a pitts type muffler, I have another Evolution that the timing is set for a tuned pipe.
Also, there should be a lot of gasser at GMA that could help. Out of 5 gas ingines, the Evolution 58 has been the hardest to adjust, but it has a lot of power and it was work all the time and effort.
How do you like the Bisson muffler? Any problems with the muffler bolts coming loose?

Thanks,
George