As mentioned before, this has been beat to death here,but jsut to quickly answer the questions. Yes it is beneficial at least to some extent that it allows more "cooler" to the intake. The tuner is the key to unlocking the power in these cars, so whether or not the CAI needs it, get one! Can't go wrong with a tuner/CAI kit from either Brenspeed(where I got mine)or Bamachips.