http://www.hughesengines.com/TechArticles/4portedintakemanifoldsupdated08272007.phpI haven't seen any dyno tests, but hughes cfm numbers tell an interesting story. For a stock big block head flowing say 230-ish CFM, the long rams look like they would provide ample flow. So as long as you're running stock or near stock heads, you should be fine and I think they would run well with a port efi conversion or a propane conversion would be fun to try. You want the intake to flow more than your heads, how much more is up for debate.
