You may also want to pull the supercharger belt off, start the car, and see if the noise is gone. If the noise is definitely related to the supercharger belt, but you don't see/feel/hear anything wrong with the coupler, look at the idler pulley. They have more of a tendency to fail than the supercharger.
Removing the belt is a simple matter of putting a ratchet wrench with the proper socket on the anchor bolt of the tensioner puller, and turning to release belt tension. Use a piece of pipe to extend the ratchet handle for better leverage.
2001 Bonneville SSEi (retired at 365,000 Kms.)
2014 Jeep Grand Cherokee Overland (yes, I know its not a GM)