Step #1 throughout this discussion is to clear the mind of any thoughts or memories involving '70's cars with "Ram-Air" hood scoops, etc, that in reality ... didn't even go through the hood!
Mind cleared? Memories erased?
Think: Pressurized Air Box (Oooooommm... Zen achieved...)
Let's move on...
Here's a very interesting short study on "Ram Air" technology, as applied to a few different bikes. In the end, these guys did a pretty good job in remaining unbiased, and also did their best to maintain the test at an objective, professional level. It may very well be something to look into...
Sport Rider-Ram Air Test of sport bikes on the motorcycle dyno
Note that this is "Part 3". Scroll down to the bottom, and click on Parts 1 and 2 for the full story, and more complete information.
Sounds reasonable... makes technological sense.
It appears that one would gain roughly 2-3 HP at mid-range RPM's through improved cylinder filling - via the pressure differential offered/created - which would be usable to the everyday rider, if only slightly noticable. In the end, it would depend on the total investment in $$$ and time, if the investment level of these factors were reasonable, it could be something pragmatic to investigate further.
Your thoughts?
Ride safe!
Bob
Ram Air? Some tests to review... 
