I have a GP 40 size Extra. One of the nicest looking designs I have seen. Mine is the ARF. I started with an Irvine .53 in it but after a snap on take off (my fault) I sheeted the stabalizers for strength when repaiing it. I put in a Magnum .91 fs in it primarily for the extra nose weight. Wow. Ground handling is a whole new ball game. Just a click or two on the throttle and the tail is off the ground and it's on it's way. The engine is still new and I am sure after a few tanks I can get the idle down to a more reasonable rpm. Big 14X6 prop looks good on it and it is great in the air. This is one of my altime favorite planes.