[ckelly78z]

I have always heard on a header collector for a race car, they run the engine wide open on a dyno (or otherwise) until the header collecter (just downstream of the end of the header) starts turning red from the heat. They then cut off the pipe an inch or two beyond the red area.

As far as determining the equal lengths of each header tube, it does depend on how many obsticles suchas motor mounts, starters, and steering controls come into play that need to be routed around. I'm sure there is a formula out there somewhere that outlines the most advantageous diameter with which head/valves size you are using, and what the best length of each diameter should be used.

Sorry, i'm not an expert, but know just enough to keep the converstation going.

I think the manufacturers of headers are building a unit that will fit MOST applictaions. If you are truly building a deep breathing monster, then specially built hearrds are a must.