I am getting a maximum of 8000 rpm with the MVVS .77 and a 14x8 APC prop. The engine was bought used but looks like it has had minimal running. The compression is very strong with a distinct pinch at TDC. I am running it a bit on the rich side with 5% Cool Power. The engine is also running with the stock MVVS muffler (not the tuned muffler). I plan on using this engine with an APC 14x4W on the Aeroworks Extra 300 .60-.90 . The top rpm sounds a bit anaemic . Any experience/data with the above mentioned props/muffler/fuel combination would be most appreciated. Thanks.