I would assume that he would just cut and rotate the pipe to fit. It would be fine if he does that. If he cuts sections out, it just may run goofy. The shorter the pipe, the less torque it will have. A fatter pipe will make it "pipey", which means all the horsepower will be at high RPM's. Race bikes or sleds with two strokes, have short and fat pipes. One for each cylinder. They are too difficult to ride on the street. An everyday two stroke sled will have a long and fairly skinny pipe for more low end torque. Two stroke street bikes have two long and skinny pipes. There were a lot of racing go karts, outboards, snowmobiles, and motorcycles made with no expansion chambers at all. Just straight pipes. They ran just fine that way, but a little better with the pipes. In any case, his trike will be just fine with whatever it ends up with. Should have way more power than it will ever need at all RPM's. A Kohler 440 should have at least 50 H.P., and the trike probably came with 5 H.P. That's 10 x the original power, so it will rip no matter what pipes are on it.