My Airaid intake definitely improved sound inside the car. You hear a much more noticeable growl from the intake when you get on the throttle.
If you installed a CAI and didnt notice a difference in throttle response or power, try detaching your negative battery terminal and leaving it disconnected for 15 minutes. You won't lose your radio station presets or your trip meter readings, but what this will do is clear all of the learned parameters in the ECU. When you reconnect the battery terminal, take the car for a short drive. 10 minutes or so should be sufficient. The ECU will relearn its intake parameters with the larger flow of air from the new intake being taken into account. This should allow you to pick up the missing power you hadn't noticed present before.
Here is a link to the install article for the Airaid CAI.