6.7l On the down pipe at the elbow where it turns down and back to the rear it is expanded like a emission component. is this so or can it be removed for performance upgrade.
You are seeing the DPF (diesel particulate filter). That must stay. Most popular companies build DPF back systems if you want a little more sound and flow.
I'm thinking it's the NOx absorber if it's the first thing in the exhaust system your talking about. jim
I'm with Bourdon. That's an awefully expensive exhaust to muck with. If your state or province isn't emissions testing yet, it likely will be before you wear the truck out and you won't pass without that exhaust in place at least to the DPF. And once you're that far back, there's little to be gained by replacing that straight-through muffler and massive exhaust pipe.