I agree with 1jimbo, I flew 2 with OS .40fp and they flew great, will fly a surprising long time on 4 ounces of fuel, longer than my dads with a Magnum .28, and if balanced right will glide like a buzzard, kinda looks like one too if you get it way up there. The .40fp will pull it straight up until it is outta sight, if you run an 11X5 prop on it it won't even slow down when you pull vertical. With a 9X6 it will fly fast enough, but isn't a rocket. I also flew one with a TT pro .40 with a tuned pipe, sounded like an INDY car on full speed passes, but had problems with flutter tearing the hinges apart, more fun with the .40fp, but not nearly as fast. I would sheet the wing before adding a .40 and tuned pipe again, if I did that tho, I'd thin it up and shorten the span just a little to go real fast.

Have fun

Austin