Ultimate engines are made by the prestigious O.S. and Novarossi brands. The characteristics of these engine adds to the Ultimate line all the best possible features you can have in a nitro engine, specifically power, performance and tuneability. Choose from the silky smooth square stroke of the M3X or the maximum torque of the long stroke M3R, but if you are looking for a great engine on a budget the M5 tuned will surpass all expectations.