I wouldn't worry about top rpm you're getting (on a newer engine) as much as whether the carb has been set for max rpm, then richened until you can just hear it drop. You get what you get, and it will very likely change as the engine breaks in. Just keep in mind the fuel helps cool your engine. At first, when it's likely running much warmer than it will when broken in, it needs a lot more fuel to keep it cooled down. That will change as it breaks in too!
A lot of guys running acrobats and 3D types run 19x8 and 20x6. For 3D I like the 20x6 to keep the rpms up for quick throttle response and max acceleration, and the extra diameter to increase the amount of air blowing over the control surfaces. 20x6 will act like a big air brake when you pull the throttle back too, pretty much slowing the plane right now. Awesome for setting up for a short approach. That's me though. No hard right or wrong here, just encouraging an open mind on what the right prop is for you and YOUR plane! -Al
Last edited by ahicks; 02-17-2019 at 05:17 AM.