Muffler vibrates

[asshole]

I recently had an aftermarket muffler put on my car and the shop that done it replaced everything from the cat converter back. Now when I am driving or even if I am just revving up the engine while sitting still the muffler will vibrate up and down about an inch. Does anyone know what I can do to stop this?

Thanks

[MileHighCougar]

Sounds like to me the muffler shop didnt anchor the muffler properly!! I would take it back to them and tell them to fix it!!