I have a Evolution 61NT that I'm putting a tuned pipe on. Any ideas for the starting point for the length of the header?

I would start with the header sized so that the length between the face of the piston and the high point on your pipe is 17". You can then shorten it from there to reach your maximum rpm with the prop you will use.

Pete<br type="_moz" />

Thank You. At least now I'll have a statring point.

JIm