[Grady Clay]

Replace them.

With care (and luck) you won’t break any.
If you do, having the engine on the stand makes the extraction of the broken stud remnants relatively easy.
Yes, not as easy as when you have the heads in your hands.
(Very difficult in the 911.)

It is useful long-term service to remove the exhaust occasionally (before rust makes it difficult).
Cleaning, painting, new hardware and gaskets keep things looking new and extend the life of expensive heat exchangers, catalytic converter and muffler.

Best,
Grady