typical stock exhaust

[SierraDan]

At work I deliver aftermarket parts and we have 06 and 08 Duramax box-vans. The 06's have what looks like maybe 3" pipe with a DPF, cat and muffler. The 08's on the other hand have what looks like the stock exhaust for the redesigned HD trucks, with the weird looking tip. Those have just the cat and DPF, no muffler. Is this typical for all 08-up HD trucks or is this a commercial option?

[Mark13]

The 2006 doesn't have a dpf. It should just have a cat and a muffler, may have a resonator under there also. It's 3.5" pipe iirc on my 06.
The 08 sounds right, the dpf's are restrictive enough mufflers are not usually needed.

[oldred95]

Actually the 07-10 LMM trucks with the DPF did have a muffler too. Its the 11+ trucks that don't have a muffler.

Duramax G vans. That just sounds so wrong. Makes me hurt just thinking about it.

[SierraDan]

I don't remember exactly what the exhaust on the 06's look like, I know for a fact it has a muffler. The 08 has 2 cat looking things, I assume 1 cat and 1 dpf but those are up close by the engine, the rest is just pipe and has nothing that looks like an actual muffler so i'm gonna say it doesn't have one. Neither of them are loud, in fact the 06's with the muffler may be louder than the 08's, since the 06 has a muffler but no dpf and it's the opposite with the 08's.

Now my next question is what is a typical diesel muffler? I can't imagine it would be near as restrictive as a stock gasoline muffler, otherwise the turbo would never be able to build boost.

I wish we could put a full 4" turbo-back exhaust on the trucks, delete the EGR and tune them. They'd get tons better mileage and be much more enjoyable to drive. At the very least just run one emission part, the least restrictive which i'm guessing is a cat, the dpf looks more restrictive.