The pieces plug up the muffler and create back pressure.

----- Original Message -----
From: "Melvin Mudgett-Price" <mprice@ACMEX.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, August 25, 2004 1:57 PM
Subject: Re: Failed Emissions Check

Thanks everyone for the replies. I put a new muffler on yesterday and
the old one had a ceramic honeycomb material in it. I thought this was a
part of the muffler that had broken down.

After reading the posts about getting a new cat I researched them and
found they contain a honeycombed ceramic element. I gas this had broken
down and worked its way into the muffler so it looks like a new cat will
be the answer.

Anyone know how this was affecting performance?