Bug: 2287 CFM
Bird: 4605 CFM
Buzzard: 5994 CFM
If you have a huge amount of butterfly area, getting a low, smooth idle will be difficult. In some cases, I've seen the butterflies CLOSED and the engine still idles too high. A guy has to start covering nozzle body vent holes to get the idle down in that case.
If it's naturally aspirated, a bug flows more air than you're likely to ever need.
I read a couple of things a long time ago that concluded there was no real benefit to scooping air from forward vs. down into a vertical opening on the drag strip. Land speed might be another story.
Spud