For revup engine.

http://www.wallaceracing.com/header_length.php

Saw this calculator, and I was curious to try to figure out what is the optimal primary header tube size. I know this doesn't take into account shorty vs long tube, but I'd still love to figure out.

 

I don't know the specs, but I believe that general consensus is that longtubes create the most power, as well as the most noise. No clue about what primary size is optimal, though, good luck with that. One of the more technically minded members (cleric) will most likely be by eventually to give his gift of VQ wisdom.

 

Definitely understand why longtubes do, but there's no central resource for comparing shorty headers, which would be cool for those of us working on our DDs, especially in states that are very restrictive