I also have one with OS 46FX at front end of motor mount, alum spinner, and battery was behind fuel tank. I also used epoxy for tail feathers and had no trouble with balancing the bird. The plane is a lightweight so little things like using light tailwheel, light pushrods and heavier main wheels may help bring your balance forward. Your magnum is a screamer so you won't need to worry about reserve power even with all that extra weight. I can get unlimited vertical with just OS 46. Don't forget to get flaperon mix turned on so you can so this bird to a walk on landing to show off to your buddies. Mine can land slower than a trainer with flaperons on.[:-]