http://forum.2gn.org/viewtopic.php?t=44915 If you go with a weld in unit, get a weld in flex joint with a 2.5" minimum ID, and cut the factory flex joint off. http://forum.2gn.org/viewtopic.php?t=66375 Also, for information's sake, it is illegal to install a used cat from another same, or different...