RE: MVVS45 pitts muffler
The Bisson Pitts muffler for a ZDZ 60 will indeed bolt right up... I have one on my MVVS 45 that's installed in a Wild Hare Edge 540. I am currently using a Bolly Carbon 22-8 and getting 7,000 rpm on the ground.
It's a great engine and have had excellent support from David Moen of MVVS Canada.