Yeah I have only ran maybe 5 oz of fuel through it. I have a Gms 32 and have never tried a smaller prop on it. I usually run a 10x5 or 11x4. The R528f kinda worries me. I have only ran it the one time but the vibration seem to be a lot between like 12k and 15k rpms. I re balanced the prop and it didn't help much. It might have been my test stand or something. I will find out when spring gets here. I think I will be happy with the power it has when I get comfortable with it.