Put it on the .40 size UCD. Guys are running .90's on them anyway. Lighten up everything possible and you'll still have decent wingloading. If you have doubts, send me the engine and I'll put it on my NIB Extra 260 profile. I'll post a video of the flight performance. Then maybe send your engine back. Or you could just try it on the .90 size plane and let us all have some real 3D type feedback on the engine.