ORIGINAL: vertical grimmace
I think for your pattern plane the OS .25FX or .32 would be the best choice. You can always add a pipe but I do not think you want Max RPM for pattern. Are you trying to go fast or have torque for vertical? I would even throw out the Saito .30 or .40 engine for this application. The .40 is basically the same size as the .30 and both are close to the size of the .25's. I love my little .30 Saito.
I should have mentioned it is an old style ballistic pattern ship, so yes I want it to rip. I am not flying pattern with it, just blasting around and having fun with a small smooth flying aircraft.
Thanks for all the replies, guys. I was looking at weights and the OS 32 does seem to be a winner here. I have a TT 36Pro, but it is a couple ounces heavier than the 32 for only a touch more power. From the sound of it, the 32 would like a Jett muffler?
Mark