Hi! Today I did some testing with various props on mu ASP 52 with the Hatori #400 pipe. I turned out that this engine swings a 14x6 hapily at above 10100 RPM. This more or less the same as a .91 four stroke. Noise level was comfortable with this setup. I consider this as a strong reading and can recommend this combo to everyone who is looking for low noise and high power to weight ratio. I flew 2 tanks with this setup on my Katana 40 3D, and there was no sign of overheating.