I can go ahead and tell you that engine isn't going to be powerful enough to do anything more than small loops and any horizontal maneuvers. It won't be able to get the Kaos up to the speed where it really performs well, and it won't pull it vertical well enough to get good scores even in novice (if you plan to compete). I have a Kaos and I have that Magnum engine on a Cub. It's barely enough power to putt around the field in a .40 size Cub. If you want a 4 stroke in it, you'll need at least a .65 from one of the more powerful brands like Saito, and preferably a .70. That said, you're going to have more torque issues from the big prop the 4 strokes turn, and it will make your flying more difficult. You're much better off using the engine that Bridi designed the plane to fly with, which is a hot ball bearing .40-.46. I have a Thunder Tiger .46 Pro in mine, and it is appropriately powered. Not overpowered, but enough to make nice big loops and hammerheads if I want it to and it will pull the plane through a big enough top hat to score well. Quite a few pilots put OS .55 AX's on the Tower Kaos to give it enough speed to knife edge well, but then you're getting into torque issues again.