Ultimate Guide to L5P Duramax Delete Kits (2017–2020 Chevrolet & GMC Trucks)

What is an L5P Duramax Delete Kit?

An L5P delete kit is an aftermarket upgrade package designed to remove or bypass restrictive factory emissions hardware on 2017–2020 6.6L Duramax engines. These emissions control systems typically include:

1. L5P Delete Pipes / DPF Delete Kit: Replaces restrictive factory exhaust sections with high-flow piping such as the 2017-2025 6.

   6L GM Duramax L5P 4" Cat & DPF Delete Pipe or a full exhaust upgrade like the 2017-2025 6.6L GM Duramax L5P 5" Downpipe-Back DPF Delete Exhaust System.

2. DEF Fluid Delete Duramax Hardware: Bypasses or removes the DEF tank, heater, pump, and injectors to eliminate DEF refill requirements and limp mode triggers caused by sensor failures.

    

3. L5P Tune and Delete Kit (ECU Custom Tuning): Re-flashes or unlocks the factory engine control unit (ECU) to adjust fuel mapping, disable emissions codes, and unleash additional horsepower and torque.

    

L5P Duramax Model Year Comparison (2017–2020)

To help you find the exact fitment for your truck, the table below breaks down key specs and compatibility considerations across different model years:

Key Benefits of Deleting DEF and DPF on Duramax Engines

1. Enhanced Fuel Efficiency

Factory DPF regen cycles burn extra diesel fuel simply to clean out trapped soot. By running an L5P full delete kit, your engine operates more efficiently, resulting in noticeable MPG gains during highway cruising and heavy towing.

2. Maximum Horsepower & Torque

Stock exhaust systems create significant exhaust backpressure. Installing L5P delete pipes such as the 2017-2025 6.6L GM Duramax L5P 4" Downpipe-Back DPF Delete Exhaust System reduces exhaust restriction, enabling your turbocharger to spool up faster and deliver smooth, immediate power across the RPM band.

3. Eliminate DEF System Failures

Deleting DEF on Duramax trucks eliminates common failure points like faulty reductant heaters, DEF fluid quality sensors, and pump malfunctions that can put your 2020 GMC 2500 or Chevy 3500 into limp mode unexpectedly.

What is Included in a Complete L5P Full Delete Kit?

When shopping for the best delete kit for L5P Duramax trucks, ensure your package includes all core hardware and software components listed in the table below:

How to Choose the Best L5P Delete Kit

When selecting a Duramax diesel exhaust fluid delete kit, consider the following factors:

1. Material Quality: Opt for T409 or T304 stainless steel if you live in northern climates with snow and salt road treatment.

    

2. Exhaust Diameter: 4-inch systems are ideal for daily driving and towing, while 5-inch systems offer a deeper, more aggressive exhaust note.

    

3. Engine Longevity Upgrades: Beyond exhaust piping, adding a CCV Reroute Delete Kit for 2017-2025 Duramax L5P 6.

   6L and an 6.6L Duramax L5P EGR Cooler Delete Kit (2017-2025) helps prevent oil mist and hot exhaust gases from fouling your intake system.

Common Mistakes to Avoid

One of the most common mistakes is buying a delete bundle without confirming the exact model year, pipe size, and ECM/ECU compatibility. Another mistake is skipping the tune, which can lead to fault codes or limp mode after installation. Before ordering, verify whether your truck needs an E41 ECM or E42 ECM solution, along with the correct block-off plates, can bus plug kit, and coolant reroute hardware if your package includes those components.

Can you delete an L5P without a tune?

No. A delete hardware setup alone is not enough. The truck typically needs a compatible tuner or ECM unlock package to avoid warning lights, drivability issues, and fault codes after the dpf and egr components are removed.

How much does it cost to fully delete an L5P?

The price range for a full delete bundle varies based on the parts included, whether you choose a 5-inch exhaust or 4-inch system, and if you add an ECM unlock and tuner. Installation can also add cost if you choose a professional install instead of a DIY install. Most complete setups require about 6–10 hours to finish depending on experience and tools.

Is it good to delete a L5P Duramax?

Many owners choose a full delete for reduced backpressure, better towing response under heavy tow load, and fewer emissions-system-related failures. However, delete kits are not legal for on-road use in many areas and may conflict with the Clean Air Act, so they are generally intended for off-road or competition use only.

How much HP is a deleted L5P?

Power gains depend on the tune, supporting hardware, and truck setup. With the right full L5P delete package, some owners see substantial horsepower and torque gains compared with stock, especially when paired with optimized tuning and free-flowing exhaust.

Conclusion

Upgrading your truck with a Duramax L5P delete package unlocks the true potential of GM’s 6.6L diesel platform. By pairing high-flow L5P delete pipes with specialized EGR/CCV modifications and a custom tuner, you achieve better fuel economy, higher reliability, and superior overall driving performance.