L5P Delete Kit: Complete Buying Guide

An L5P delete kit commonly refers to a combination of exhaust, EGR, CCV and engine-management components designed for certain 2017–2025 Chevrolet Silverado and GMC Sierra HD trucks equipped with the 6.6L Duramax L5P engine.

However, not every L5P kit fits every model year, truck configuration or intended application. A 2017–2019 truck may require different exhaust connections from a 2020–2025 truck, while some complete packages are limited to an even narrower range, such as 2020–2023.

This guide explains the major types of L5P components, how CAT-and-DPF pipes differ from downpipe-back systems, when a 4-inch or 5-inch exhaust may make sense, and what fitment details must be verified before ordering.

Quick Answer: Which L5P Delete Kit Do You Need?

The correct L5P setup depends primarily on four questions:

1. What is the truck’s exact model year?

2. Is it a pickup or a Cab & Chassis model?

3. Are you replacing a specific exhaust section or looking for a broader package?

4. Is the vehicle used in a legally permitted competition, closed-course or otherwise exempt application?

For shoppers who only need an exhaust section, a CAT-and-DPF pipe or downpipe-back system may be the relevant category. An EGR kit addresses a different part of the engine system, while a CCV reroute kit is intended for crankcase ventilation. A complete package may combine several components, but its model-year coverage is usually more restrictive.

Do not purchase a kit simply because the product title contains “L5P.” Always verify the model year, flange style, wheelbase, cab configuration and included components.

L5P Kit Comparison

4-Inch vs. 5-Inch L5P Exhaust

A larger pipe is not automatically the better option. Choose according to underbody clearance, adjoining components, wheelbase and the desired exhaust character.

What Is Included in an L5P Delete Kit?

There is no universal component list for every product sold as an L5P delete kit. The term may describe one individual part or a package containing several different systems.

Common categories include:

• A CAT-and-DPF replacement pipe

• A downpipe-back exhaust system

• An EGR valve and cooler hardware kit

• A CCV reroute system

• Exhaust clamps, hangers, hoses, plates or mounting hardware

• Application-specific engine-management equipment in certain complete packages

Before ordering, compare the product’s actual contents rather than relying on the general “delete kit” name.

A pipe-only product will not include every component found in an All-in-One package. Likewise, a CCV reroute kit does not replace the exhaust system, and an EGR hardware kit is not the same as a downpipe-back exhaust.

1. L5P CAT-and-DPF Pipe

A CAT-and-DPF pipe is designed to replace a specific section of the original exhaust assembly. It is generally a more focused product than a complete downpipe-back system.

DieselPerf offers a dedicated 2017–2025 L5P 4-inch CAT-and-DPF pipe. The product page lists:

• 2017–2025 6.6L Duramax L5P fitment

• Chevy Silverado and GMC Sierra 2500HD/3500HD applications

• 4-inch pipe diameter

• T-409 stainless-steel construction

• A 2 mm wall thickness

• A factory-style four-bolt connection requirement for applicable 2020+ trucks

• No compatibility with Cab & Chassis models

These fitment details should be verified directly against the truck before ordering. 

Who should consider this type?

This configuration may be relevant when the buyer needs a specific replacement exhaust section rather than a full system. It is important to visually confirm the connection point and determine whether any existing aftermarket exhaust components are already installed.

2. L5P Downpipe-Back Exhaust System

A downpipe-back exhaust system begins after the truck’s existing downpipe and replaces a larger portion of the downstream exhaust than a short replacement pipe.

The 2017–2025 L5P 4-inch downpipe-back DPF exhaust system is listed for Silverado and Sierra 2500HD/3500HD pickups with the 6.6L L5P engine.

The product page identifies T-409 stainless steel, a 4-inch diameter and a factory-style four-bolt flange requirement for applicable 2020–2025 configurations. It also states that the system does not fit Cab & Chassis trucks. 

CAT-and-DPF pipe vs. downpipe-back

The main difference is the amount of exhaust being replaced.

A CAT-and-DPF pipe is a more limited section. A downpipe-back system replaces a longer portion of the exhaust beginning after the factory downpipe.

Choose between them based on:

• The parts currently installed on the truck

• The condition of the remaining exhaust

• The desired pipe diameter

• Wheelbase and bed length

• Existing aftermarket modifications

• The exact factory connection style

3. Combined 4-Inch and 5-Inch L5P Exhaust Options

Buyers who are still comparing configurations can review the broader 2017–2025 L5P 4-inch and 5-inch DPF pipe selection.

This listing includes several configurations, including CAT-and-DPF, downpipe-back and muffled options for different year ranges. Because the selections cover multiple styles, the dropdown choice is just as important as the main product title.

The page lists 2017–2025 L5P compatibility at the product-family level, but individual variants have more specific year ranges. For example, some downpipe-back selections are divided between 2017–2019 and 2020–2025. 

4-inch vs. 5-inch L5P exhaust

A 4-inch exhaust is usually the more conservative choice. It is easier to package under many trucks, commonly matches other diesel exhaust components and may provide more clearance around the frame, spare tire and suspension.

A 5-inch exhaust is physically larger and is often selected for its deeper exhaust character or for a build that already uses compatible larger-diameter components. However, larger is not automatically better for every truck.

Consider the following before choosing:

Actual sound, temperature and engine behavior depend on the complete vehicle configuration. Avoid selecting a pipe size based only on advertised horsepower or fuel-economy claims.

4. L5P CCV Reroute Kit

CCV stands for closed crankcase ventilation. The factory CCV system manages crankcase gases and routes them according to the original engine design.

An L5P CCV reroute kit for 2017–2025 Duramax trucks is a separate product category from an exhaust or EGR kit.

The DieselPerf listing identifies:

• 2017–2025 L5P engine compatibility

• Silverado and Sierra 2500HD/3500HD pickup applications

• A direct-fit component design

• Restrictions for certain 3500, 4500 and 5500 Cab & Chassis commercial trucks

The product page should be checked carefully because pickup and commercial chassis configurations may use different layouts. 

Is a CCV reroute the same as an EGR delete?

No.

The CCV system manages crankcase gases. The EGR system recirculates a portion of exhaust gas through the engine under factory-controlled conditions. They are separate systems with different components, installation locations and compliance considerations.

A CCV product should not be treated as a substitute for an EGR kit, exhaust pipe or complete package.

5. L5P EGR and Cooler Kit

The EGR system and EGR cooler form another distinct part of the L5P engine and emissions architecture.

The 2017–2025 L5P EGR and cooler kit is listed for 6.6L Duramax L5P applications and includes application-specific plates, hoses, seals and mounting hardware.

The product page lists 2017–2025 compatibility and identifies steel plates, coated fasteners and a dedicated dipstick bracket among its specifications. 

Because the EGR system is integrated with the truck’s engine controls and required emissions equipment, purchasers must confirm that the intended use is legally permitted. This article does not provide instructions for disabling emissions monitoring or altering factory software.

6. L5P All-in-One Delete Kit

A complete package is intended for buyers who need several matched components rather than one individual part.

The DieselPerf 2020–2023 L5P All-in-One kit is listed for Chevy Silverado and GMC Sierra 2500HD/3500HD trucks equipped with the 6.6L Duramax L5P.

The listing combines exhaust hardware, EGR-related components and engine-management equipment. It also identifies T-409 stainless steel and billet-aluminum hardware. Most importantly, its listed fitment is 2020–2023, not the full 2017–2025 L5P range. 

Who should consider an All-in-One package?

A complete package may simplify component matching for a qualifying application, but it requires more careful verification than a single pipe.

Before ordering, confirm:

• The truck is within the exact 2020–2023 range

• It is a supported Silverado or Sierra HD configuration

• The ECM and existing engine-management equipment are compatible

• No previously installed components create duplication

• The intended use complies with applicable law

• A qualified diesel professional has reviewed the complete parts list

Do not assume that a 2020–2023 package will fit a 2024 or 2025 truck merely because both use the L5P engine designation.

L5P Model-Year Differences

The L5P Duramax was introduced for the 2017 model year, but the surrounding exhaust, electronics and chassis configurations were not identical throughout the entire production range.

2017–2019 trucks

Many exhaust products divide 2017–2019 trucks into a separate variant. When shopping, verify the original connection, wheelbase and current exhaust configuration.

2020–2023 trucks

These trucks commonly require the applicable factory-style four-bolt exhaust connection described on the DieselPerf product pages. They also fall within the listed range of the referenced All-in-One package.

2024–2025 trucks

Individual exhaust, EGR and CCV pages may list coverage through 2025, but the referenced complete package stops at 2023. Use a product specifically listing the later model year rather than assuming earlier components are interchangeable.

Pickup vs. Cab & Chassis Fitment

One of the most common buying mistakes is assuming that every Silverado or Sierra with an L5P uses the same exhaust routing.

A conventional 2500HD or 3500HD pickup may differ substantially from a commercial Cab & Chassis truck. Frame length, tank placement, exhaust routing and mounting points may change.

Several DieselPerf L5P pages specifically exclude Cab & Chassis applications. Therefore, verify the following before purchasing:

• Pickup or Cab & Chassis configuration

• 2500HD or 3500HD model

• Cab length

• Bed length

• Wheelbase

• Single-rear-wheel or dual-rear-wheel configuration

• Existing exhaust diameter

• Factory flange and clamp style

When fitment is uncertain, provide the VIN, model year, cab configuration, bed length and a clear photo of the existing exhaust connection to the seller or installer.

What to Check Before Buying

Use this checklist before ordering any L5P kit:

1. Confirm the engine

Verify that the truck has the 6.6L Duramax L5P, not an earlier LML, LMM, LBZ or another engine generation.

2. Confirm the exact model year

Do not use a broad “2017+” assumption. Product variants may be divided into 2017–2019, 2020–2023 and 2020–2025 ranges.

3. Identify the vehicle configuration

Determine whether the truck is a standard pickup or a Cab & Chassis model.

4. Inspect the existing connection

Confirm whether the truck uses the flange, clamp and downpipe connection required by the selected product.

5. Review existing modifications

A truck with an aftermarket downpipe, partial exhaust or previous CCV modification may require a different combination of parts.

6. Check every included component

Make sure the package contains the required clamps, hangers, plates, hoses, seals and mounting hardware.

7. Verify legal eligibility

Confirm that the vehicle and intended application are legally eligible before purchasing emissions-related hardware.

Common L5P Buying Mistakes

Buying by engine name alone

“L5P” identifies the engine family, not the complete exhaust and chassis configuration.

Ignoring the variant dropdown

A product family may contain multiple pipe diameters, model-year ranges and muffler options.

Confusing a short pipe with a full exhaust

A CAT-and-DPF pipe and a downpipe-back system replace different amounts of the exhaust.

Assuming 5-inch is always better

The larger diameter requires more space and does not automatically produce a better result for every build.

Overlooking Cab & Chassis exclusions

Commercial trucks often use different frames and exhaust routing.

Assuming the complete kit covers every L5P year

The referenced All-in-One package is listed for 2020–2023, even though individual component pages may extend through 2025.

Frequently Asked Questions

What is an L5P delete kit?

It is a general market term for hardware—and sometimes engine-management equipment—intended to alter one or more factory DPF, EGR, DEF/SCR or CCV-related systems on a 6.6L Duramax L5P truck. The exact included parts vary by product.

What years use the L5P Duramax?

The products covered in this guide are listed for L5P trucks from 2017 through 2025. However, individual configurations and complete packages may cover narrower year ranges.

Will one L5P kit fit every 2017–2025 truck?

No. Model year, connection design, pickup versus Cab & Chassis configuration, wheelbase and existing modifications all affect fitment.

What is the difference between CAT-and-DPF and downpipe-back?

A CAT-and-DPF pipe replaces a defined section of the factory exhaust. A downpipe-back system replaces a larger section beginning after the existing downpipe.

Should I choose a 4-inch or 5-inch exhaust?

Choose based on available clearance, existing components, desired sound and complete system compatibility. A 4-inch system is generally easier to package, while a 5-inch system is larger and typically produces a deeper exhaust character.

Is a CCV reroute kit part of the exhaust?

No. It modifies the routing of the crankcase ventilation system and is separate from the truck’s main exhaust piping.

Is an EGR kit the same as a DPF pipe?

No. The EGR system is located around the engine and intake system, while the DPF is part of the exhaust aftertreatment assembly.

Does the All-in-One package fit a 2024 or 2025 L5P?

Not according to the referenced product listing. That package is specifically listed for 2020–2023 L5P Silverado and Sierra HD trucks.

Do L5P exhaust products fit Cab & Chassis trucks?

Several products referenced in this guide specifically state that they do not fit Cab & Chassis models. Confirm the vehicle configuration before ordering.

Is an L5P delete legal for street use?

In the United States, the Clean Air Act prohibits tampering with required emissions controls and prohibits devices intended to defeat those controls. These products must not be used to modify public-road vehicles illegally. State and local requirements may impose additional restrictions.

Final Buying Recommendation

The best L5P product is not necessarily the package with the most components or the largest pipe diameter. It is the product that correctly matches:

• The exact model year

• The factory connection style

• The pickup or Cab & Chassis configuration

• The existing exhaust setup

• The intended legally permitted use

• The buyer’s actual replacement scope

For a single exhaust section, compare the dedicated CAT-and-DPF and downpipe-back options. For crankcase ventilation, review the CCV reroute kit. For EGR-related hardware, use the dedicated EGR product page. For a broader package, confirm that the truck falls within the All-in-One kit’s narrower 2020–2023 fitment range.

Always inspect the truck before ordering and have a qualified diesel professional confirm compatibility and legal eligibility.

Product specifications and availability may change. Review the current product page and applicable regulations before purchasing.