Agreed, an opposed cylinder layout works great in a motorcycle. They're smooth, easy to maintain, and have a very low C.G. And the old airhead BMWs were cooled very well with the cylinders sticking out in the wind. I'm surprised flat engine layouts aren't more popular. I think the only motorcycle companies using it are Honda, BMW, and Ural. Porsche and Subaru are the only cars. Am I missing any?