If you are referring to the short ram, or CAI (cold air) dont try and believe people when they tell you it adss 10 tp 15 horse. Just like a guy I know who thinks K&N DOES add 15 HP. Anyway, one of the above will give you better throttle response, but as for whp, i dont know... i thnk someone posted a dyno here before about it.... just try a search
Also, I have seen a picture of someone selling a carbon fibre hood with a scoop that likns to a short ram... ths might be what you are looking for. Hopefully someone here knows what i am trying to say and know the company.... i cant remember.