If you want speed all you have to do is look at what the pylon boys are running. A .46 on 15% PowerMaster, a #8 plug, and a 9.5 X 7 APC prop seems to be about optumum. Usually the ground RPM is set around 14.6k figuring it will gain more when it "unloads" in the air. In the WM T-34 which is raced a lot that equates to around 92 MPH on a straight run using radar to measure. Funny thing is engines seem to do as well or better with the baffel in. Oh well, check with your local pylon racers. They know how to go fast and turn left.

Roger