ORIGINAL: P47Pilot
I use a Saito125. This is a bit overpowered, but I intend using the plane for flying a Basic Imac program with with a 3-blade propeller, so the extra power will come in handy. It fits well within the cowling with a compact muffler. It will fly well at 25% throttle which means the engine most of the time will not be struggling.
Gotta love those Turbo Headers.