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Call or Text (352) 722-5295How exhaust leaves a 2007.5-2010 GMC Sierra HD LMM
Exhaust from each bank of the LMM Duramax collects in a cast manifold. On the passenger side, an up-pipe with a flex bellows section carries it across to the turbo, a water-cooled Garrett GT3788VA variable-vane unit. Behind the turbo come the downpipe, the diesel oxidation catalyst and the diesel particulate filter, which the engine cleans with active regeneration using late post-injection of fuel. There is no DEF system on the LMM; that arrived with the 2011 LML. Everything on this page bolts in ahead of the turbo, so none of it changes the aftertreatment.
What fails and why
On a WT, SLE or SLT Sierra of this age, leaks ahead of the turbo fall into two groups.
- Cracked up-pipe bellows. The passenger-side bellows is the signature LMM exhaust failure and the most common exhaust complaint on 2001-2016 Duramax trucks. It's an age and heat-cycle problem with no published mileage threshold. Symptoms include a metallic screech or tick under load, lost boost and drive pressure, higher EGT, soot streaks on the firewall and exhaust smell inside the cab.
- Manifold, flange and gasket leaks. Cracked manifolds, loose flanges and worn-out gaskets leak the same way, get worse over time and slow turbo spool. They are often misdiagnosed as turbo trouble.
Either leak can also throw off the DPF pressure and temperature sensors and cause extra regens. Before you replace a DPF on a Sierra that regens constantly, fix the leaks, verify the sensors and let it finish full regen cycles on the highway.
Stock replacement vs. upgrade
Think of the repair in three sizes. A pipe-only repair fits when the passenger bellows is the only failure, and PPE's 116120916 is built to bolt to the factory manifold. A pipe kit is the next step: the 116120710 is an OEM-length high-flow up-pipe kit. Manifolds and pipes together make sense when the manifolds are cracked or the flanges won't seal, and PPE's 116111800 pairs high-flow manifolds with up-pipes in one package. Across the aftermarket, the upgrade for this joint is heavy-gauge stainless with a welded bellows in place of the failure-prone factory flex joint, so read each product page for how its pipe is built.
What we carry
PPE supplies the core parts: the passenger-side replacement up-pipe, the OEM-length high-flow up-pipe kit, the high-flow manifolds with up-pipes, a manifold-to-up-pipe gasket set, the up-pipe-to-EGR-cooler gasket for 2007.5-2010 trucks and an up-pipe bolt set. MAHLE adds gaskets for the manifold-to-up-pipe and up-pipe-to-turbo joints. For hardware there is the Gator Fasteners UPBK66 heavy-duty up-pipe bolt kit and ARP 672-1003 chromoly bolts in M10 x 1.50 x 30. The rest of the system, from the downpipe back, lives in our exhaust collection.
Fitment notes
The pipes, manifolds and EGR cooler gasket here are listed for 2007.5-2010 Duramax; the other gaskets and bolts carry wider 2001-2016 listings. The LMM came only in the GMT900 Sierra 2500HD and 3500HD from mid-2007 through 2010, so a 2007 Sierra Classic with the LBZ is a different truck. Up-pipe kits do not cover the LGH engine in Savana vans. On hardware, check bolt diameter against the flange holes before install: some aftermarket up-pipe bolts are undersized, and reusing the factory bolts is the fallback. Verify by VIN or use the fitment checker on each product page.
Frequently asked questions
Should I replace the manifolds when I do the up-pipe?
Only if they are cracked or the flanges won't seal. Manifold and flange leaks slow spool just like a cracked pipe, so inspect them while you're in there. If they're bad, PPE's 116111800 kit pairs high-flow manifolds with up-pipes in one package.
Do new up-pipes change my DPF or other emissions parts?
No. The up-pipes and manifolds sit ahead of the turbo, while the DOC and DPF sit downstream of the downpipe. Replacing them leaves the factory aftertreatment as it was, and sealing a leak can help the DPF sensors read correctly.
Can I reuse my factory up-pipe bolts?
Yes, if they're in good shape. One up-pipe maker warns that some aftermarket bolts are undersized for the flange holes and recommends reusing OEM hardware. If yours are damaged, compare the replacement bolts to the flange holes before you install them.
Is a cracked up-pipe tied to mileage?
No mileage threshold has been published. Bellows cracking is tied to age and heat cycles, so inspect the pipe on any Sierra of this age, whatever the odometer says.
Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell at our shop in Wildwood, FL.