The downpipe end connection may be different. Pull the cat pipe off and look to see what kind of end it has.
I using my stock exhaust as it would be too costly for me to upgrade from 3.5" to 4" or bigger in my cab n chassis frame. I just completed the installation of the MBRP downpipe and cat test pipe. I had to install their downpipe as the end is designed to mate to their cat test pipe. The stock downpipe wouldn't fit up. Their end is flat flange and the stock down pipe is the flared end.
See additional close-up pics of the connection.
Last edited by jagular7; 11-19-2010 at 10:46 AM.