This is a topic that has been discussed here in the past as well as covered in the Mopar Performance engine books regarding ideal collector extension length. Taking another look at this myself and came across a nice in depth article regarding collector extensions. Many may have been there done that and moved on to other things, have used the paint or crayon method to find the ideal length but I think this is a good read nonetheless for anyone on the path of tuning & testing.
Header Design Comments - Cheap Performance Gains.
With my setup and the 1-5/8” Dougs, runs at the track have developed a blued pattern (after jetting for Max Mph) that ends at about 7-1/2” on these 12” stainless Pypes extensions. I’ll likely source some cheap ones to hack down vs. chopping on these for the time being.....see what it yields at the track.
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What have some of you found during your track based exhaust tuning? :)
