Interesting...

When you buy a Borla Kit, they supply you with a new "device" ( ) to replace the factory resonator/cat.

I HIGHLY doubt they would be able to include a new cat WITH the muffler and all that stainless tubing for less than $700. Cats are extremely expensive. Not to mention, most emissions laws (depending on state, of course) dictate that the emissions system (AKA cats) cannot be tampered with before 60,000 miles or significant damage has occurred. If a cat WAS in fact the object which needs to be replaced, Borla would have serious headaches in marketing this kit. The Crossfire setup is already a low-volume seller (compared to a Silverado, LOL) so putting one more hurdle in front of the kit (via CARB certification, lack of LEGAL tampering ability, etc.) is something I see as doubtful, at best.

But it's just a theory. Plus, don't you want cats to be relatively close to the engine, to make the chemical reaction occur more easily due to the gases being in a more excited (read, changeable) state? It seems there would be too much cooling time before the gases reached the rear "apparatus" to allow proper functioning of the cats themselves. If in fact it were a cat.

I vote resonator.

Again, just a speculation.