Hey all,
I finally tracked the vibration down. It was the forward-most bracket support for the aircharger system. I tightened the hell out of it and I think the problem is solved.
I may remove that support and place a rubber shim underneath the bracket itself, along with rubber grommets above and below the bolt connections.
The bracket was vibrtating on the fender, thus the reason I thought it was a skid plate. The sound was very similar to a skid plate vibrating on a rail or frame part.
For those of you with the K&N 66 aircharger systems, you may want to inspect your supports to verify that yoor nuts and bolts are secure. While I happily admit that I have a few loose in my head, I am sure I tightened these down to the max when I installed the system. Engine vibration may be causing the nuts and bolts to loosen on these systems.
