Did you add a skid plate? And now it makes obnoxious noise and vibrations? Try this... cheap sound dampening mat with a foil backing... I used "fat mat" because I had some left over from a stereo install.
My Honda CRF250L used to resonate in a tone that made my fillings vibrate... godawful to say the least. Now nothing... it still reflects more sound up than no plate but no more nasty resonance.