I don't think there are any official numbers (Lampoon would have to confirm), but most people who have CRABS say they notice a difference. (better throttle response, better mileage, etc.) If I had the money right now, I would lay down for the CRABS.
Lampoon, since you are the owner, do you have any idea? can you provide any data?
OP - simple performance says faster air is in and out faster the car is. the colder the air the more dense. the more dense the more fuel it can have. if the air is cold it mean performance. the CRAB heat shield does help but if you can get a "Full Length" intake you will DEFF keep the hot engine air away from your intake charge.
Now Crabs has posted some temps but that is WITH a MPD Ram Air Hood. this pulls ambient air straight in to the intake thru the ram air hood and is not going to be the same result for the general public who does not have a Functional Ram Air Hood.