First flight yestereday after running one tank through the engine on a test stand. This is my second Graupner, the first had an OS61. This plane flew like a rocket. Off the ground on its own in about ten feet. So fast that I had to fly it at 1/3 to 1/2 throttle. The engine is using a Pitts muffler, and still pulls like a mule. Good golly Miss Agnes, what a combo. I dont know how long the Tower 75 will last, but its warranteed for two years, and if only lasts that long, thats fifty a year. The difference between the OS61 and this engine is astounding. Started it with three flips of a chicken stick.