Video: How to Choose the Correct Header Primary Size
Watch this Summit Racing Quick Flicks video to learn how your header’s primary diameter affects performance. You will learn some basic rules for how to choose the best header primary size for your application.
Great info! Too bad I didn’t know more about this in the late 60s and early 70s. Will need headers probably sooner than later. I have more to think about now. I haven’t watched the whole series yet but I will prior to ordering.