Duramax DPF Delete Pipes & Exhausts: Which Fits Your L5P, LML or LMM?

Which Duramax Generation Do You Have?

Per GM's owner's manual, your engine code is the eighth character in the VIN.^[1] The DPF & CAT Delete Pipe for the L5P fits 2017–2023 trucks. An L5P can also run the 5" Down Pipe-Back Full Exhaust Delete. A second DPF & CAT Delete Pipe fits the 2011–2016 LML. A 2007.5–2010 LMM takes the 5" Downpipe-Back Full Exhaust Delete.

Going by the badge alone is like sizing a socket by eye. Close isn't good enough here, and a wrong guess can eat a whole weekend under the truck.

Reading Your Engine Code Off the Truck

Skip the guesswork. The VIN is in the front corner of the instrument panel, on the driver side of the vehicle.^[1] Find that eighth character and you've got the code this whole page is sorted by.

L5P, LML or LMM — which one is yours? On this page, an L5P owner is choosing between two options, while the LML and the LMM get one each. That's no knock on the older trucks; it just means the call gets made fast once you know the code.

Why the Code Matters More Than the Badge

Here's the thing — how many engines do you think wear the Duramax name? The LZ0 Duramax 3.0L turbo diesel is the second generation inline-six turbo diesel over the previous LM2.^[3] The 2.8L LWN is a Duramax turbo diesel engine.^[2]

Neither one is the truck this page is about, and that's exactly why the badge can't settle fitment on its own. Whatever's under the hood, start with the code, then the model year, then the body style.

Keep an eye out for half-years, too, and read every year range on this page all the way to the decimal. Match a part to the badge instead of the code and you're gambling with a weekend you'd rather spend on the dyno.

Which Pipe or Exhaust Fits Your Model Year and Chassis?

The L5P DPF & CAT Delete Pipe covers 2017–2023. The 5" Down Pipe-Back Full Exhaust Delete also fits the L5P. The 5" Downpipe-Back Full Exhaust Delete fits the 2007.5–2010 LMM. The LML DPF & CAT Delete Pipe covers 2011–2016. Check your downpipe connection: a V-Band clamp at the downpipe means you have the 2015 early model, and a 3-Bolt Flange means you have the 2015.5 later model.

Fitment works like a two-key lock. Model year is one key and body style is the other, and turning just one of them leaves the door shut.

Both L5P Options Run 2017 Through 2023

A lot of guys assume the full exhaust stops a year short of the pipe. Read on before you believe that.

Here's how the 5" Down Pipe-Back Full Exhaust Delete lines up on an L5P. This fits the 2017 through 2023 Silverado 2500HD/3500HD and Sierra 2500HD/3500HD with the 6.6L Duramax, all pickup cab and box lengths. It does not fit Cab & Chassis trucks.

So don't let the calendar make this call for you. Pick on what you want the exhaust to do.

Pickup or Cab & Chassis: The Other Half of Fitment

Body style is the key a lot of guys forget to turn. Start with the 5" Downpipe-Back Full Exhaust Delete for the LMM. It does not fit Cab & Chassis trucks, and it doesn't fit LML (2011–2016) or earlier Duramax generations.

Same drill for the pipes. The LML gets its own DPF & CAT Delete Pipe. It's designed for pickups and is not built to fit Cab & Chassis models, which would require modifications.

And the L5P's DPF & CAT Delete Pipe? Cab&Chassis models will require modifications to be made for the pipe to fit. If your truck is a Cab & Chassis, flag it early and save yourself the headache.

Telling the Two 2015 LML Downpipe Variants Apart

The 2015 model needs a closer look before you order, because there are two variants. They're not interchangeable, so match the variant to your truck. LML owners, get the flashlight out and look at the downpipe connection before you do anything else.

Can't tell from under the truck? If you're unsure, call (888) 830-2588 Ext 2 before ordering. Snap a photo of the connection while you're down there, since it settles the question fast once you're on the phone.

The Four Parts at a Glance

The whole lineup sits in one place below. Note the LMM part starts at 2007.5, not at a round year.

What Does the Factory DPF System Actually Do, and Why Does It Regenerate?

The exhaust system has a Diesel Particulate Filter (DPF) to reduce vehicle emissions.^[5] The DPF will clean itself as part of normal operation.^[5] The Engine Control Module (ECM) monitors fuel consumed, hours of engine operation, and miles driven.^[5] The DPF system is not capable of self-cleaning at idle.^[4] Manual DPF regeneration is only available on Fleet and Commercial vehicles.^[4]

Let's break it down. Everything in this section comes from GM's owner's supplements for the Duramax in L5P model years, so if you're running an LML or an LMM, read it as background rather than your truck's spec sheet. Think of the DPF as a lint trap that's supposed to empty itself.

What Happens During an L5P Self-Cleaning Cycle

It's easy to mistake a self-clean for something breaking. During self-cleaning there will be a change in the exhaust sound and engine idle speed.^[4] Along with this, a burning smell and reduction in fuel economy may be noticed.^[4]

So if the idle shifts between rounds and you catch a hot smell off the back of the truck, don't start pulling parts. That's the filter doing the job it was built to do. Keep a note of when it happens and what the truck was doing, because patterns are easier to spot on paper than from the seat.

Why Regen Runs on the ECM's Schedule, Not Yours

A regen cycle doesn't check your calendar before it starts. The ECM keeps score the whole time, and the timing is its call, not yours. You don't get to pick the moment, so you plan around it.

All that idling in the staging lanes? It isn't doing the filter any favors.

Want to force the issue yourself? To confirm your truck has manual regeneration, check the Vehicle Service Parts Identification label (SPID) for RPO code FPF.^[4] Manual regeneration can only be used when the DPF has become at least 90% full.^[5]

So even on a truck that has it, a lightly loaded filter isn't something you can regen on a whim. Fleet and commercial trucks get the option; everybody else waits on the ECM.

How the DPF Differs From the Separate DEF System

This is where a lot of guys mix up the DPF and DEF. Diesel Exhaust Fluid (DEF) is used with diesel engines to reduce the amount of regulated emissions produced.^[4] The fluid level in the DEF tank must be maintained for the vehicle to run properly.^[5]

Different fluid, different tank, different job from the filter. Nothing on this page touches the DEF side of the truck — this guide is about the DPF and CAT section specifically.

What's the Difference Between a DPF & CAT Delete Pipe and a Full Exhaust System?

The 5" Down Pipe-Back Full Exhaust Delete is built for the L5P. This system runs from the downpipe back, replacing the OEM DPF and CAT sections with a free-flowing pipe in a larger diameter. The DPF & CAT Delete Pipe is made for the LML. Your factory muffler stays in place. The 5" Downpipe-Back Full Exhaust Delete is the LMM's full exhaust.

The pipe runs from the downpipe back, replacing the factory DPF and CAT with a wider, free-flowing tube. Think of the full exhausts as re-plumbing the whole run, and the delete pipe as swapping out one section of it.

Why Some Listings Show a Shorter Pipe and Others a Full-Length System

Plenty of guys figure a delete pipe is just a cheaper full exhaust. It isn't, and the LML pipe shows exactly why. The install guide for the DPF & CAT delete pipe is written for the 2011-2016 LML.

It only replaces the section of your factory exhaust that contains the emissions parts. Those are the two barrel shaped parts in your exhaust near the middle of your truck. Everything in front of them and behind them stays put.

The front end of the delete pipe connects to your down-pipe and the tail end of the delete pipe connects to the tail pipe, just before the bend over the rear axle. One section out, one section in.

Pipe Diameter: The LML Pipe Versus the 5-Inch Full Exhausts

Back to that LML pipe for a second. The delete pipe is the same diameter of your factory exhaust system, so it will be a perfect fit. Now look back at the larger diameter and wider tube on the 5-inch full exhausts.

So which do you want: stock-size simplicity, or more pipe than the factory gave you? Answer that and you're most of the way to a decision.

Planning the Job on the Lift

Whichever way you go, lay the new pipe out under the truck, next to the run it replaces, before anything comes off. You'll see exactly how much of the exhaust you're swapping, and you'll know where your hands and your stands need to be.

Have a helper on the other end for the longer pieces. A second set of hands keeps the pipe from swinging into the frame while you start the clamps.

What's Included With Each Delete Pipe or Exhaust System?

The 5" Downpipe-Back Full Exhaust Delete belongs on the LMM. Everything you need comes in the box: the 5" T-409 stainless steel full exhaust, the OEM-style hangers and clamps, and a step-by-step installation guide. The DPF & CAT Delete Pipe fits the LML Duramax. It's high-quality T-409 stainless steel, mandrel-bent for optimal exhaust flow, with OEM-style hangers and clamps for a factory-fit installation.

A box that shows up short is worse than a truck that waits an extra day for the right part. So here's exactly what's confirmed for the LMM exhaust and the LML pipe before you order.

What's Confirmed for the LMM Full Exhaust

The box list above is the complete list for this exhaust — pipe, hardware and the guide. T-409 stainless gives you better corrosion resistance than aluminized steel, so it's built to outlast the truck. Lay it all out on the shop floor before you crawl under, so you're not scrambling mid-install.

What's Confirmed for the LML Delete Pipe

Here you know what the pipe is made of, how it's bent and what holds it up. What you won't find is a bolt-by-bolt count of the box, and that's not a red flag. It just means you check before you assume.

Where Contents Aren't Itemized, and Which Listings Call for a Tune

If a part's page doesn't itemize the box, check that product's own page before you order rather than assuming one product's parts list matches another's. Then there's the tune.

Running the 5" Down Pipe-Back Full Exhaust Delete on an L5P? You'll need a compatible delete tune to keep DPF codes away.

Same question for the LMM's 5" Downpipe-Back Full Exhaust Delete. You'll need a compatible delete tune to prevent DPF codes.

Putting the DPF & CAT Delete Pipe on an LML? You'll need a compatible delete tune to prevent check engine codes after install. Budget for the tune as a separate purchase — the pipe and the exhaust are the mechanical half of this job, not the whole job.

What Should You Expect During Installation?

The 5" Downpipe-Back Full Exhaust Delete is the LMM option here. No welding required, and free shipping is included. One thing to know up front: on this 5" LMM system the front hangers are not used. The DPF & CAT Delete Pipe fits the L5P Duramax. The CAN bus plug install guide for the 2017-2019 L5P says the CAN bus plugs must be installed.

The good news? The LMM exhaust skips the welder entirely. Bolt-on or not, though, this is still lift or jack-stand work, not a floor-jack-only job.

What the LMM Full Exhaust Needs, and What It Doesn't

OEM-style hangers and clamps lock it in without modification. The pipe is self-supporting through its other mounting points, and that's completely normal for this configuration. So when you're flat on your back wondering why the front hangers are empty, you haven't lost a part.

Dry-fit everything before you snug anything down. A few minutes laying the pieces out on the floor beats a long afternoon on your back.

The L5P CAN Bus Plug Step

This one's easy to miss if you treat the job as pure exhaust work. Skip the plugs on an L5P and you're chasing a problem that was never about the exhaust at all. And whatever year your L5P is, ask us before you assume the plugs are optional.

Instruction Guides and Support for Both Delete Pipes

We get it — nobody wants to be halfway through an install with a question and nobody to ask. Say you're installing the DPF & CAT Delete Pipe on an L5P. We send you a step-by-step instruction guide and have a full time support staff to help you with any questions you may have on the installation.

Installing the DPF & CAT Delete Pipe on an LML instead? We send a step-by-step instruction guide and have a full-time support staff to help with any questions, and you can open a support ticket on our website if you hit a snag. Keep that guide on the bench where you can see it, not buried in the cab.

Checks Before the First Fire-Up

Once everything is hung, walk the whole run with a light. Make sure every clamp is snug, nothing rubs the frame, and the tune question is settled before the key turns.

Which Delete Should You Buy for Your Truck?

Start with your engine code. The DPF & CAT Delete Pipe for the 2017–2023 L5P is priced $599.00 to $687.00. The 5" Down Pipe-Back Full Exhaust Delete for the L5P is priced $929.00 to $999.00. The DPF & CAT Delete Pipe for the 2011–2016 LML is priced $475.00 to $625.00. The 5" Downpipe-Back Full Exhaust Delete for the 2007.5–2010 LMM is priced $999.00 to $1,149.00.

Price is the tiebreaker, not the starting line. The engine code already narrowed the field, and on an L5P the real question is how much of the exhaust you want to replace.

When Either Option Works for Your L5P

So which one belongs on your truck? If you want the whole downpipe-back run replaced on your L5P, the 5" Down Pipe-Back Full Exhaust Delete is the pick. If you'd rather keep more money in your pocket on a 2017 through 2023 L5P, the DPF & CAT Delete Pipe is the bang-for-your-buck pick.

Neither answer is wrong. It comes down to what you want the build to do on the dyno and out on the trail.

5" Down Pipe-Back Full Exhaust Delete | GM/Chevy 6.6 Duramax 2017-2023

It's the best-selling Duramax 5" full exhaust, and it bolts on across all cab and box lengths. Shipping is free, exhaust systems are final sale, and a damaged or wrong system gets replaced at no cost. Measure twice, commit once.

DPF & CAT Delete Pipe | GM/Chevy 6.6L Duramax L5P 2017-2023

You'll want this bit before the box shows up. All exhaust systems and DPF/CAT delete pipes are final sale and not eligible for a refund or return. However, if you receive a faulty product or the wrong product, we will send you a replacement.

Matching LML and LMM Trucks to This Page's Options

LML and LMM owners have an easier call on this page. For a 2011 through 2016 LML, the DPF & CAT Delete Pipe is the option on this page.

For a 2007.5 through 2010 LMM, the 5" Downpipe-Back Full Exhaust Delete is the option on this page. Once you've confirmed your engine code and, for LML, your 2015 downpipe variant, the table in the fitment section shows which part is yours.

DPF & CAT Delete Pipe | GM/Chevy 6.6L Duramax LML 2011-2016

Shipping is included in the price. All delete pipes are final sale, but a faulty or wrong product gets replaced. So match that 2015 variant before you commit.

5" Downpipe-Back Full Exhaust Delete | GM/Chevy 6.6L Duramax 2007.5 -2010 LMM

It ends regen cycles and cuts exhaust restriction, giving your LMM room to breathe through a 5" T-409 stainless steel pipe. For an LMM build that's been fighting its filter, that's the whole point.

Before You Order: Variant, Body Style and Final Sale

Run this checklist before you commit. Confirm the engine code, confirm the body style and, if your LML sits in the split year, confirm which downpipe connection you've got.

Final sale means the checking happens before the box ships, not after. Get those right and the part that shows up is the part that bolts on.