I used an OS FS 1.20 on mine and mounted it inverted. was very easy to do and didn't require removing much of the cowl. The only real issue is the length from the firewall to the spinner backing plate. It's a little longer than stated in the instructions but I checked it out with VF and they said it's ok as long as you make sure the cowl is mounted flush at the top since it won't fit tight all around. I also installed a Dave Brown 120 size motor mount and mounted it at the same height as the factory 90 size but I offset it about 3/16" to the left (as viewed from the rear towards the front) to counter the 2 degree right thrust. This made the prop shaft come out in the center of the hole in the cowl. Balance can be a problem. I used Sullivan flying wires, dubro heavy duty 60-90 control horns and mounted a 6 volt battery to the bottom of the wing saddle to help with the balance. I also used dual servos on the elevator and mounted an ultralight throttle servo just behind the fuel tank. I haven't checked the final balance, but I'll let you know how it comes out. Was very close when I tested last. After I maiden it, I'll post a few pics. I think it's bad luck to take pics before that first flight and LANDING...