I have the Great Planes ARF 89" Spacewalker with a G26 converted to EI and lightened considerably. It balances perfect now but was quite nose heavy with the Zenoah all stock with mag. I removed about 1lb. and 2 oz. form the Zenoah when I converted it. The GP Spacewalker recommends a 120 size four stroke and with my Saito 91 it flew well but was tail heavy so I had to add nose weight. The plane now weighs 11.5 lbs. with the modified Zenoah and the engine makes 17.3 lbs of static thrust so it has no limits vertical. It will pull out of a hover which I know it can't maintain because it has no inboard ailerons but I just slow it down in vertical and when it starts torque rolling I punch the power and off it goes like a rocket. It flies just like the one in the RealFlight G3 sim. Kinda like a big Cub but more manuverable. Flies upside down as good as it does right side up. Just a very graceful, slow, fun bird. Relaxing to fly.