I'd like to relate my contrary experience.

First of all, I've heard of other reasons not to use SS fasteners...
that they may accelerate corrosion in the materials they contact, that
they may not meet hardness/strength stardards required i.e. 10.9,
12.9... and I'm sure there are may others, but...

When I first replaced parts of my exhaust system 7 years ago, every
single fastener was corroded to an unrecognizable nub. Even with
vise-grips, sawz-all, oxy-acetylene torch, and various other implements
of doom, I ended up spending the better part of a day writhing and
cursing in the dirt. I vowed never again to suffer the same fate. I went
right to the hardware store, picked up a set of SAE stainless nuts &
bolts and reinstalled the exhaust.

A few years later when it was time for exhaust replacement chapter two
(this is Maine, so if your exhaust lasts more than two years fortune has
smiled upon you), I was able to remove every single fastener without
issue. They were definitely tight and made an absolutely horrid
squealing sound when they were undone, however I was able to accomplish
the task in a fraction of the time required previously, with nothing
more than a couple of wrenches. No powertools, no expletives, nothing
catching on fire. I know - where's the fun in that? :)

Anyhow, based solely on my personal experience, I'd be one to recommend
stainless fasteners for the exhaust. As always, feel free to discount my
story and do as you please!

Cheers,
Doug Fitz-Randolph
Freeport, ME

>Date: Wed, 17 Jan 2007 12:34:03 -0500
>From: Geza Polony <gezapolony@SBCGLOBAL.NET>
>Subject: Warning! Do not use...
>
>stainless steel bolts on your muffler/catalytic converter.
>
>The more experienced among us know this already. I thought I'd beat the
>corrosion problem by using M8 stainless bolts and nuts for my new Bus Depot
>cat and muffler. Once they heat up, there's no way to loosen them. I don't
>know what happens to the steel, but it sure isn't any labor saver. The heads
>just break of when you crank them. So much for good intentions.