I have about 1.5 gallons through the NGH GF38 so far, Timing reset to 28-30 deg BTDC, Stock short open header, 30:1 Klotz gas burner in 91 octane no ethanol gas;
Static test:

Master Airscrew 20x8 Wood 5500 rpm
Xoar PJA 20X8 Wood 58-5900 rpm
Xoar PJA 20X6 Wood or
Xoar PJA 19X8 Wood 6500 RPM

Hope that helps. I have been flying it on an 80" ugly stick. Good power for general sport flying. If you want to serious Aerobatics it should probably
go on a little smaller airplane (75"?). I have a lot of years in RC but this is my first gasser. Interesting but a real learning curve from Electric or glow.

D.H.