Wanderer

Just got back from a short drive after changing the spark plugs. I was revving the engine to about 6k and as the revs drop I heard the strangest noise. It was a loud out of sync rev drop of something else that was spinning. It sounded very similar to those toy cars that had the ripcord that when pulled would cause the wheels to spin.

The car is a 2008 Cayman S with 42k on it.

Any thoughts?