This link has some more specific info on it...
http://www.ws6.com/ramtest.htm

Just wondering since at higher engine speeds the ram air runs out of steam as compared to the hood open would it be effective with a high rpm setup or do all "cold air" kits and the like do the same? I guess I am asking if its really worth it the extra $. Thanks.

 

This is how I understand it and I aint no engineer so excuse the lay-terminology.
There is a 'boundary layer' of air moving along the top of the hood, or across any surface high velocity air travels. The 'boundary layer' is slow moving, so the only way to utilize a 'ram effect' would be in getting the scoop up high, out of the boundary layer. Look at an old Hemi race car scoop (68 Super Stock Baracuda is a good example).
If you're going to funnel, high pressure air in then you need to get above the boundary layer, either that or put the duct somewhere at the nose of the car. Pulling air from the boundary layer is not bad either (cowl induction)..... hell it's much cooler than the air under your hood.

-Mindgame