Yes, my evo 26 spins 18x6W APC prop at 8500 rpm.... The first prop I had on it was a carbon fiber 18x6 Biela, and it would spin it at 7800.... after one gallon of fuel I replaced the prop with the APC one and with out making any other changes I gain 500 rpm.... after second gallon I leaned out the engine and I can get it to spin the APC prop at 8700, but that was just nuts, and I was afraid that it may be running too lean, so I richened the mixture a bit and it seems very "happy" now.... As far as "unburned" oil and mess is concerned, gasoline engines should run clean, with out making mess like their glow counterparts - all my other gas engines (DA 50R, ZDZ40) run clean - and keep in mind that I use the same fuel/oil mixture and oil brand in all my engines. I talked to Horizon about it - they had no idea what’s going on with the motor - the only thing they suggested is that I am mixing too much oil - I don't see how - 40:1, that is what they say in the manual.....