Judging by the performance I'm getting with 14x6 on my FA-80 with Turbo-Header, the 20% may be enough. Idon't like to run plastic props if I can avoid it. I prefer wood. Ihave a wooden 13x8 on it now and may not be able to fit a 14" inch due to ground clearance ...unless Iadd larger tires (which equal more weight).
Iappreciate your advice and will give it serious consideration if I decide to go with a plastic prop.
I'm told that the OS .91 develops a bit more HPthan the Saito so, 30% heli may help make up the difference. I'll give it a try. Ido know that 30% helps cool the engine better during our hot summer months when we have temps in the high 90's and lower 100's. One of our club members advised me to use it during that period and, along with some cowl baffeling, helped to keep the FA-80 cooler.

RJ