I read posts all the time speculating about whether it helps to have a bigger downpipe or not. Someone posted this on NASIOC a while back. It's by far the most scientific explanation for this I've read. I don't know whether or not the guy is for real, but he sounds knowledgeable:
http://forums.nasioc.com/forums/show...ett+hyperbolic
Scroll down to the longest post on the page.