No weight needed to be added. I assembled the plane per instructions and placed the radio and battery in a large piece of foam in the compartment just foward of the cockpit. The plane balanced right on the mark. The prop shaft that comes on the engine is a perfect fit in the cowl. I don't know why the guy who reviewed it in MAN left the box on and paid for a new prop shaft(a very expensive part,BTW). If you check on this site you will find quite a few different gassers have used on this plane. I have only seen 2 of these planes fly, and both had the Fuji. I have been very pleased with this setup and would recommend it to anyone. This is my first gasser so I can't say I have a lot of gas experience to draw from, but I think it is a pretty good setup. I think th Fuji 64 might be a bit much for this plane. The 50 shakes the hell out of the plane and the 64 might exceed the integrity of the airframe.