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Exhaust & DPF for the GM Duramax

Turbo-back and cat-back diesel exhaust systems, downpipes, and exhaust hardware that free up flow and give the Duramax a deeper diesel tone — including DPF-back options for LMM/LML trucks.

1 part

Match exhaust & dpf to your engine

The single thing to know before you buy is which aftertreatment your engine has, because it decides both what fits and what's street-legal.

Generation What it means for this part
LB7 / LLY / LBZ (2001–2007) Pre-DPF. These use a catalytic converter, so cat-back and turbo-back systems — plus a downpipe from the turbo — are the common upgrades.
LMM (2007.5–2010) The first diesel particulate filter generation. The street-legal upgrade is a DPF-back system that keeps the factory filter and replaces everything behind it.
LML (2011–2016) DPF plus SCR/DEF aftertreatment, and the turbo's vanes provide the factory exhaust brake. DPF-back again for a street truck.
L5P (2017+) Full DPF and SCR aftertreatment with the most factory flow of the family. DPF-back is the street path here too.

Before you buy

  • → 4-inch is right for stock-to-mild and most tow rigs; 5-inch earns its keep behind a bigger turbo, more fuel, and a tune.
  • → Stainless over aluminized if you drive through road salt or plan to keep the truck.
  • → Mandrel-bent pipe flows better than crush-bent — check the bends, not just the diameter.

Not sure which engine you have? Decode it from the eighth digit of your VIN with the Duramax VIN & engine code decoder, or map your year and platform in the generations & fitment guide.

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Parts in Exhaust & DPF

Read before you buy: exhaust & dpf guides

Written for this exact system, generation by generation.

Best Duramax Exhaust Systems

DPF-back vs. cat-back vs. turbo-back, diameter, materials, and why flow drops EGTs.

Best Turbo Upgrades

Backpressure is the turbo's problem first — exhaust and turbo choices are one decision.

Tuner & Programmer Buyer's Guide

A freer exhaust pays off most with a tune that monitors EGT and boost.

VIN & Engine Code Decoder

A 2007 truck is either an LBZ or an LMM — and they need different exhaust.

Parts that go with these

Turbos Air Intake Performance

Exhaust & DPF: common questions

DPF-back, cat-back, or turbo-back — which does my truck need?
It follows your engine's year. Pre-emissions trucks (LB7, LLY, LBZ) run a catalytic converter, so cat-back or turbo-back is the usual upgrade. Emissions-era trucks (LMM, LML, L5P) have a diesel particulate filter, and the street-legal choice is DPF-back — the factory DPF stays and everything behind it is replaced.
Does a bigger exhaust really lower EGTs?
Freeing up flow lowers backpressure, which helps the turbo spool cleaner and shaves exhaust gas temperatures — a real benefit towing heavy up a grade. The horsepower headline comes from tuning and fueling, not the pipe. Treat the exhaust as the outlet half of an airflow package.
Which exhaust fits a 2007 Duramax?
Depends which 2007 you have. GM overlapped the LBZ in the older classic body with the LMM in the new GMT900 body that year, and only the LMM has a DPF. Decode the eighth digit of the VIN before you order — the two take different systems.