I bought a H9 Ultra Stick and put a Saito 56 on it. They come with a nice aluminum motor mount that clamps the engine so you can change engines without redrilling. that part works well but I had to glue a piece of 5/16" square steel key stock 6" long on the horizontal stabilizer to balance the plane.

I removed the engine mount and replaced it with a Great Planes plastic mount, pried off the piece of key stock and went flying. The battery is against F-2 and everything else is in its normal place. that is how much more a metal mount weighs