Here's my experience with a used Moki 2.10
Xoar 20-8
Omega 5%
Bisson Pitts
6600 with the needle valve fully open. Was not getting enough fuel even with large tube and drilled out clunk. Installed Perry pump and got to 6950. Engine now ran great but seemed weak on a 15.5lb Extra. It would just hold a hover, but barely.
Trimmed off pinched portion of muffler tubes and got 7200. Not much improvement flying as It still never seemed to come on step.
APC 20-8 with same setup as above
7900 rpm.
Very ugly looking propeller, but what a difference in flying. Pulling out of a hover was effortless and straight line speed is now appropriate for the model. I hope to find a better looking prop with the same performance as the APC.