I have a Zenoah G38 with a slimline muffler. It currently turns a APC 18x8 Wide blade at 8300rpm. I would like to get a little more verticle out of my extra without gaining anymore speed. I have recently tried a bolly carbon 19x6 but the revs on the motor rose to over 8800rpm and the plane flew way to slow. I was thinking of going to a bolly wood 20x8 or an APC 20x8. Is this to much prop for the engine? What other props do you recomend?