Find out where it is hitting the body... Do this: Turn your car on, get under your hood, get someone to slightly rev your engine or open your throttle yourself from under the hood, if you know what and where it is. Once you find the rattle, go to Wal-Mart and find some subber padding that is sticky on one side... Stick it to the piping of the CAI in between where the CAI metal is and where the body of your car is.

This is just COMMON SENSE.