I have a Vance and Hines sidewinder header, I converted my early head to studs already, does this header need the split collars behind the flanges to tighten? The ones I have are smaller radius than the pipe ends but when I mount the header without them I run out of threads before the pipe gets tight. Maybe a few washers?
I had this header on a cb900c previously but don't remember this issue.
I'm going with the washers, check back later, and yes I have new crush washers installed. It appears this is how a Kerker mounts also.