Those are factory "Cherry bombs" I bought a second factory exhaust to build a custom setup for my '12. When I cut that off It's straight through. The cats are indeed part #4 in the diagram above. They know some people cut the cats off so they moved them as close to the manifolds as possible. Right before the "suitcase" muffler was the clamp to remove the muffler and tailpipes. hence the "cat back" system was easily replaceable.