Steve, you could try the S&S muffler.  I have these in stock for $120.  They
are a little louder than stock (any "turbo" muffler will be) but I have
actually felt improvements when putting these on customer's vans (of course
their old mufflers could have been deteriorated inside and actually
restricted, but who knows).  Just an option.
The other nice thing about these mufflers is that they eliminate those
expensive carrier brackets ($55 each) and the straps that go on the top of
the stock muffler ($20 each) since they have their own brackets welded to
them.
Just FYI.

Thanks,
Ken Wilford
John 3:16
www.vanagain.com
Phone: (856)-765-1583
Fax: (856)-327-2242