There is a 5-year warranty registration card that comes with the Bosal cats that you get from FPC Groton. It appears that the warranty needs to be filled out by a dealership. Is it possible to get the warranty when an individual installs it? Since there's hardly any way to install the cat incorrectly, it would seem pretty unfair to not get the warranty on the part just because you put it in yourself.

One small annoyance about the Bosal cat: The OEM cats have threaded holes to accept the mounting bolts that attach it to the front exhaust pipe, but the Bosal cat just has regular holes with no threads, so you'll have to have 3 new bolts (a little longer than the original bolts) with nuts and lock washers at the ready to install it. You'll want to get copper bolts/nuts if you can find them, or else the yellow-goldish colored ones that I think are called "Type 6" or something like that. Also make sure you get a new gasket.