I'd second the Super Tigre 61 ABC choice, especially if you look on the RCU marketplace on this forum. You can find them new in box, for less. Resale value on .60 size engines is at an all time low. That AX 55 isn't going to do that plane justice. It's an over rated engine, for .40 size planes, not 60 size. I had one on a Hangar 9 Pulse XT(40 ARF), and couldn't see any difference from a Super Tiger 45 but more fuel consumption.