Since I haven't seen anyone else post this yet, I figured I'd do it.
These guys did some experiments to see if and how well ram-air actually works on sportbikes. I wouldn't take any of it as gospel, but i found it pretty interesting.
"Ram-Air, what's it worth?" (with a ZX-9R)
"Ram-Air test" (on a desert track)
"Ram-Air test: Part deux" (on a dyno)