Bill, I have three of the SS40S plain bush engines. Two from Ebay, one new. Still haven't decided what to mount the current one in, excellent power their only downfall being weight. I have only bench run one but man, what a silky, even run they give. I'm thinking of a Sig Banshee with the wing moved forward 1/2 to 2 inches to compensate for the weight plus muffler. The Supercool props article is very encouraging with this engine.