[V6-12v] Experience changing cats

[Tom Christiansen]

Folks,

As I was crawling around under my 1994 90S (B4) patching the down pipe
for the driver's side cat with Quicksteel, I discovered that the cats
shouldn't be as hard to replace as I had feared. Everything is
reasonably accessible. Most of the bolts downwind of the cat look
pretty pristine, but I wonder about the three nuts on the exhaust
header. On most cars those are notorious for seizing up. But I noticed
that they are lock nuts. So maybe I could be in for a bit of luck...
Does anyone have experience to share in this regard?

Is it three studs in the header? Or three bolts? Will I need to cut
the bolts or do the nuts generally come off without too much fuss? Are
the bolts secured from the top so they won't spin as I turn the nuts?

Would you replace just one cat? Or is it normally encouraged to
replace both at the same time?

Thanks,

Tom