Sorry, they are Flows

 

My problem sounds very similar to yours. I have borla s types and I can just tap it and it will make a buzzing noise. There is plenty of clearance for the hangers, clamps are on very tight and it's not touching any part of the car. It almost sounds like it is still the hangers even though it's only in contact with the rubber. Not sure what would cause it but its so annoying...