RCRainman, your best bet is as others have said, follow Sig's recomendations. The ideal trainer is one with a little extra power, but light weight. Adding the .46 will probably work, but it'll end up heavier than necessary. Get yourself a reasonably priced .25, build the plane light, and learn to fly it on the wing, not the prop. When you're done learning, keep it for practicing landings, testing new radio equipment, etc. Or, if you do a good job building it, and it's in good shape when you're done, sell the plane and engine to another new beginner.