Originally Posted by BillBoost37
In my experience the S2 exhaust has the O2 bung far enough back that you can swap the cat and still have 4 or more inches of piping before the O2.
Not sure which one you are looking at, as I didn't look it up... but please keep in mind you do not need one with the O2 built into it.
Could depend on the year...
On my '98 LeSabre, the stock cat was nearly 2 feet long, a wide oval in cross section, with the bung virtually bult in to the cat...could be the CA emissions package though, I dunno.
On the '04 LeSabre, it is more like what you describe...the stock cat is only like 1 foot long, is cylindrical, and there'* a good foot (or more) of pipe before the bung. (Although that car has the CA emissions RPO code, also)
Maybe you could post us a few pictures of your current stock cat / O2 bung setup.