I have had a few buzzing noises develop recently. The one in the rear was a completely loose heat shield that I pulled out. Assumed the noises up front wer the same I changed my rotors this past weekend and got a look underneath. When I slapped on the exhaust I could hear a small rattle. Not a failed cat and none of the heat shields were loose. I did see a suspicious hose clamp and wanted to ask what others thought The shield clamped to the exhaust is form fitting and one side
That definitely was not done at the factory... There's a reason it was put there and you'll probably need to remove it and take pics of what's underneath for us to help figure out the mystery. Maybe part of an anti-theft system that was removed at some point?