I don't think you necessarily have to have a Vanagon mechanic to do good
muffler
work.  You just need to find a reputable muffler shop.  I took my 87 Westy to
a local
shop in Houston (Mike's Muffler) that has been in business for 25 years and
they were
real professional.  Ordered me a Bosal muffler and called me when it came in.
 Put
it and a cat. and new tailpipe he also ordered in with no problems.  Looks
and sounds
great.  Of course, the old grizzled fellow actually doing the work looked
like he'd seen
many a muffler in his day ;-)
james