You might want to check out Larry Meaux's site at
www.maxracesoftware.com/PIPE395.htm. Larry is a very nice guy and knows a LOT about Header Design. He offers a really cool
Header Sizing software program. I used it to calculate tube sizes, collector size, etc. and mock up my design for a set of stainless steel Headers for my 70 Olds 442 Drag Car. The Headers were actually built for me by GP Headers. They did a great job.
Hope this helps.
Harold