12X11 prop seems a bit big for a .50 size engine. I have always run a 10X6, 10X7 or 10X8 on my Como .50 or Jett Fire .50. Always felt 10K RPM wouldn't be enough. The Como ran 15k RPM & the Jett runs 16k both on 15% & tuned pipe. But if that works for you on your Zen 50, I might give it a try. I'll be experimenting to find the right match anyway. Thanks for the info.

And vprpilot, I'm green with envy over your flying site. Very, very nice.