RE: Sig 1/5 scale piper cub
A twin has got to be the first choice, it looks and sounds so good. I ran a Magnum 70 FS on mine, which was way overkill, so as to turn a scale 14" prop. Of course, I never ran full throttle on it, and as it turned out, the plane flew better on a 13X6 than the 14X6. Go for a twin!