Cam & head upgrade 360 mag

I used to have a website that had the whole exhaust thing figured out. As engines are basically air pumps, they pump out a certain CFM of air at certain horsepower. This website showed what pipes flowed what CFM. And told you what aprox horsepower matched with what pipe. If I recall, 2-1/4 was good for just under 400. But the website seems to be down right now. This is the chart they came up with:

http://www.ls1gto.com/forums/attachment.php?attachmentid=149219&stc=1&d=1332948156

It's all backed by some math that seemed to check out to me. So that's what I run with.