I was using a 20-8 pro zinger. I made my own prop hub,carb mount and instailed my magnet too. This is the first convert fo me. I'm also working on a 21cc i tested it the other day and got 10780rpms with a 3 blade 14-9 MAS prop. I also tested it with a 16-8 APC prop and stock muffler and got 9500 rpms. I made muffler for it that got the 10780 rpms.

Thanks