M54 3.0i Exhaust Gasket Replacement at Catalytic Converter

[richardb]

Hey everyone, looking for some tips here. Our 2005 3.0i began leaking from a blown out exhaust gasket where the catalytic converters bolt to the center muffler (diagram attached). This seems like an odd spot for an exhaust leak, and is the first exhaust leak I've experienced on a modern BMW in over 10 years.

The removal of the four nuts looks treacherous, so I'm bringing this one to a local shop so they can use a torch if (when) needed. I'll be providing the shop:

Two new gaskets, BMW part number: 18107502346 (number 3 in the diagram)
Four copper nuts, BMW part number: 18301737774 (number 2 in the diagram)

Gasket being replaced is #3 in the attached diagram image.

My question is, how often do the studs strip out during this job? Is it possible this turns into a difficult job where the studs need to be drilled out from the cat pipes and replaced with bolts?

Thanks!