Proflow offers a variety of header flange sizes and shapes to mate your heads and headers. These 3/8 thick flanges are precision-cut to meet your ports, reduce warping, and prevent leaks. Proflow header flanges keep your tubes in place without the big price tag.
No more struggling to get  bolts started on 1 3/4" primary pipes with the std Windsor bolt pattern. If you have aftermarket heads with the wider 3" bolt spacing why not take advantage of that option and start your header build project with the much more convenient bolt hole position.
You will end up being rewarded with a better set of pipes and also be able to fit and remove them with ease.

Note: Due to the many variations of port position and plug angle, some minor relieving may be needed for spark plug socket clearance