Originally Posted by yellow2112

I don't know if this is a redundant post or not here but the faster the air goes in and out and the colder the air, the more power you get.

The concept of a cold air intake pipe is that the air is supposed to be drawn further away from the motor and thus cooler. It also helps that the pipe is metal which may cool the air more than the normal PVC pipe and since cold air is more dense, it will contain more oxygen and combust more completely. The higher the rate of combustion, the more power you get and the cleaner your car runs.

I agree with the other comments that you may not notice a major HP gain but in some cases it could be 20hp.

Heres a good article on cold air intakes:
http://auto.howstuffworks.com/how-mu...intake-add.htm