I have a TT 61 on a Super Hots. At just under 6lbs it is a very fast plane with no verticle limitations. I have a Master Airscrew 12/6 on it. I am suprised to hear that the TT61 is not a hot engine. I guess 6lbs is not very heavy for a 61 but it sure does pull hard. I love this engine, you guys were right , no messing with this engine. Set it up and fly all day on it.