Ok Sterling. I have a NIB 91FX. I might give it a try. Have you tried an APC prop on it? How big are the loops can you pull with that motor. Can you get giant 100 foot loops? I was not worried to much about the airframe, but now that you mention the interplane bolts I had not much thought about shaking those loose. I need to pick up a new muffler for the engine, and I might try it out first before I put the big one in it. It just gives me the hevy jevy's just putting a 91FX in a 15 pound plane. Although I must admit, I have been putting mostly 3d type craft in the air lately and I have gotten used to the power to rate ratio. At least it will make flying it a little bit more of a challange.