Brison 3.2 numbers
Brison 3.2 with standard inline muffler
MenzS 21X8 = 7600 rpm AMSOIL 100:1
Zinger Pro 22X8 = 7200 rpm AMSOIL 100:1
These numbers were verified with two different tachs.
I bought this engine used but I had it tuned at Brison and I have personally run about 12 gallons through it.
It is a monster. I prefer the 21X8 MenzS. Makes my DP Extra truly ballistic.