exhaust leak

not often...id say a bolt came loose and they blew the gasket out...i think you would be pretty safe to assume you need to have them replace the gasket.

Ive seen it happen, and had it happen to my original mac headers, what's worse is they cracked in the center of where all the tubes meet, which is damn near impossible to diagnose with them on the car, always sounds like a flange leak.

I'b be sure first they aren't leaking at the gasket or where header meets the h pipe.

Believe it or not, header gaskets are easy to change.