my .02 is first of all I doubt the CAI alone gives any real horsepower, when you buy one be aware some need a tune. This tune (not a CAI) MAY void a good bit of your wtty. The reason I bought a CAI (no tune) was for the sound I'm happy with my Airaid but I bought it used. The best one is one scored used since you can get them in the classified for $150-200!
Enjoy it but once you've started making the car yours it can get expensive
It will give power at higher RPMS where the larger cone filter will allow better airflow. The tune gives better power throughout the band, not just the higher rpms, and it will also smooth it out quite a bit. American muscle has a comparison video Stock, Just CAI, Just Tuner, and both with results. Doubt no more!