A 2018 L5P delete kit removes or disables emissions control components from your Duramax diesel engine

A delete kit for a 2018 L5P Duramax removes or bypasses the diesel particulate filter (DPF), selective catalytic reduction (SCR) system, and exhaust gas recirculation (EGR) cooler. These are factory emissions control devices that reduce pollutants before exhaust leaves the tailpipe. Removing them changes how the engine runs and what comes out of it.

Owners install delete kits primarily to increase engine performance, reduce maintenance costs on emissions equipment, and improve fuel economy. A delete kit typically includes new exhaust piping, a tuning file to reprogram the engine computer, and sometimes a new intake manifold. The work usually takes a shop between 8 and 16 hours depending on which components are deleted and how much welding is involved.

Before you consider this modification, understand that it is illegal to delete emissions equipment on any vehicle registered for road use in the United States. The Clean Air Act prohibits removing or disabling emissions controls, and the EPA can issue fines to both the shop that performs the work and the vehicle owner. Many states also conduct emissions testing that will catch a deleted truck. This guide explains what the kit does and what the legal and mechanical consequences are — not whether to install one.

Key Takeaways

  • A delete kit removes the DPF, SCR, and EGR cooler, which are emissions control devices that reduce tailpipe pollution.
  • Deleting these components increases horsepower and torque, typically by 50 to 100 hp depending on the kit and tuning.
  • Deleted trucks fail emissions testing in states that perform it, and both the owner and the shop face federal penalties under the Clean Air Act.
  • Maintenance costs on emissions equipment drop after deletion, but engine wear may increase without the cooling and backpressure those systems provided.
  • A delete kit costs between $2,500 and $5,000 installed, plus the cost of any engine tuning or custom fabrication work.

What each component does and why owners delete it

The diesel particulate filter (DPF) traps soot and ash in the exhaust stream. When it fills up, the engine automatically burns off the buildup in a process called regeneration, which uses extra fuel and creates heat. Owners delete the DPF to eliminate regeneration cycles, reduce fuel consumption during those events, and remove a component that can clog and fail. A clogged DPF typically costs $1,500 to $3,000 to replace.

The selective catalytic reduction (SCR) system injects diesel exhaust fluid (DEF) into the exhaust to convert nitrogen oxides into harmless nitrogen and water. Owners delete the SCR to stop buying DEF (which costs $5 to $10 per gallon and requires frequent refills), eliminate SCR heater failures, and remove a system that can freeze in cold climates. The SCR itself rarely fails, but the heater and injector do.

The exhaust gas recirculation (EGR) cooler routes hot exhaust back into the intake to lower combustion temperatures and reduce emissions. It is prone to internal leaks and carbon buildup, and a failed EGR cooler can cost $800 to $1,500 to replace. Deleting it removes a known failure point and allows the engine to run hotter, which some owners believe improves performance.

Performance gains and what they cost mechanically

A stock 2018 L5P produces 445 horsepower and 910 pound-feet of torque. After a full delete and custom tuning, most trucks gain 50 to 100 additional horsepower and 100 to 150 additional pound-feet of torque. The exact gain depends on the tuning file, whether the intake and exhaust are also modified, and the quality of the delete work. A straightforward DPF delete with basic tuning produces smaller gains than a full delete with aggressive tuning.

The trade-off is that the engine loses the cooling effect of the EGR system and the backpressure regulation of the DPF. Without these, combustion temperatures rise and exhaust scavenging changes. Long-term effects include faster wear on piston rings, valve seats, and turbocharger bearings. Most deleted trucks run hotter and accumulate carbon faster. How much faster depends on driving habits — highway cruising causes less stress than towing or frequent acceleration.

Deleted trucks also lose the factory engine brake function that the EGR and backpressure systems provided, which means longer stopping distances when towing and less engine braking on downhill grades. Some tuners include a separate engine brake tune to partially restore this, but it is not identical to the factory system.

Legal consequences and emissions testing

The Clean Air Act makes it illegal to remove, disable, or render inoperative any emissions control device on a vehicle registered for road use. The EPA can fine vehicle owners up to $37,500 per violation, and shops that perform the work face fines up to $43,280 per vehicle. These are not theoretical — the EPA has issued fines to both owners and shops in recent years, particularly in states with active enforcement programs.

If your state performs emissions testing, a deleted truck will fail. The test reads the engine computer for diagnostic trouble codes related to missing emissions equipment. Even if the tuner has hidden some codes, the physical absence of the DPF and SCR will be detected. Some states test every vehicle annually; others test only when you register or renew registration. A few states do not test at all, but that does not make deletion legal — it only means you are less likely to be caught.

Insurance companies are not required to cover damage to a deleted engine, and some policies explicitly exclude coverage for modifications. If your truck is in an accident and the shop discovers it has been deleted, the insurer may deny the claim. Resale value also drops significantly — most buyers either want a stock truck or are specifically looking for one that is already deleted, and the pool of the latter is much smaller.

What a typical delete kit includes

A complete delete kit for the 2018 L5P usually contains new exhaust piping to replace the section that held the DPF, a new intake manifold or gasket set to accommodate the removal of the EGR cooler, and sometimes a new turbo inlet pipe. It does not include the tuning file — that is purchased separately from a tuner and loaded onto the engine computer by the shop or by the owner using a handheld programmer.

Kits vary in quality and completeness. Budget kits ($1,500 to $2,500) include basic piping and may require custom fabrication to fit properly. Mid-range kits ($2,500 to $4,000) are engineered specifically for the L5P and include all necessary gaskets, clamps, and brackets. Premium kits ($4,000 and up) include mandrel-bent piping, high-quality gaskets, and sometimes a new intake manifold. The tuning file is separate and typically costs $500 to $1,500 depending on the tuner and how aggressive the tune is.

Installation labor ranges from $800 to $2,000 depending on the shop rate and how much custom work is needed. Some shops charge flat rates for a full delete; others charge hourly. Shops in rural areas or areas with less emissions enforcement tend to be more willing to perform the work, but that does not change the legal status of the modification.

Maintenance changes after deletion

Deleted trucks no longer need DEF, which eliminates a recurring cost and the hassle of refilling the DEF tank. You also eliminate the risk of DEF heater failure and SCR injector clogs. Oil changes may be needed more frequently because combustion temperatures are higher and carbon accumulation is faster — some deleted truck owners switch to 5,000-mile intervals instead of the factory 10,000-mile interval.

The turbocharger may require more frequent inspection because it runs hotter and works harder without the backpressure regulation of the DPF. Intercooler cleaning may also become necessary sooner. Some owners report that deleted trucks accumulate carbon on intake valves faster, which can require carbon cleaning service every 50,000 to 100,000 miles instead of the factory interval of 150,000 miles or more.

You no longer have DPF regeneration cycles, which means no unexpected fuel consumption spikes and no heat-related stress on the engine during regen. However, you have traded a known maintenance schedule for unknown long-term wear patterns. The factory emissions equipment was designed to manage heat and combustion byproducts; removing it shifts that burden to other engine components.

Alternatives if you want better performance without deletion

If you want more power without the legal and mechanical risks of deletion, several options exist. A tuning file alone (without deleting emissions equipment) can add 30 to 50 horsepower by optimizing fuel injection timing and boost pressure. The engine still has all its emissions controls, so it passes testing and remains street-legal. Cost is typically $500 to $1,500.

An intake and exhaust upgrade (keeping the DPF and SCR) can add 20 to 40 horsepower by improving airflow. A cold air intake costs $300 to $800, and an aftermarket exhaust that keeps the DPF costs $1,500 to $3,000. Combined with a conservative tune, these modifications stay legal and keep the truck emissions-compliant.

A transmission tune improves shift quality and response without changing emissions. This is often combined with a modest engine tune for a total gain of 40 to 60 horsepower while remaining legal. If towing is your priority, a transmission tune often provides more practical benefit than raw horsepower because it improves load management and reduces transmission heat.

Frequently Asked Questions

Will a delete kit make my truck fail inspection?

Yes, if your state performs emissions testing. The test reads the engine computer for emissions-related codes and detects missing equipment. Even if the tuner has suppressed some codes, the physical absence of the DPF and SCR will be caught. States without emissions testing programs will not catch it during inspection, but that does not make it legal.

How much horsepower does a delete kit add?

A typical full delete with tuning adds 50 to 100 horsepower and 100 to 150 pound-feet of torque, depending on the tuning aggressiveness and whether other modifications are done. A DPF-only delete adds less — usually 30 to 50 horsepower. The exact number varies by tuner and tune file.

Can I delete just the DPF and keep the SCR and EGR?

Yes, and some owners do this to reduce costs and legal risk. A DPF-only delete costs less and provides some of the fuel economy and maintenance benefits. However, it still violates the Clean Air Act, still requires tuning, and still fails emissions testing. It is not a legal middle ground — it is a partial deletion that is still illegal.

What happens if I get caught with a deleted truck?

The EPA can fine you up to $37,500 per violation. You may also be required to have the truck restored to factory emissions specifications. Insurance may deny claims related to the modification. Resale value drops significantly. Some states can also suspend registration or issue additional fines through state environmental agencies.

Is there a way to delete the truck and still pass emissions testing?

No. Emissions testing specifically looks for the presence of emissions equipment and reads the engine computer for codes indicating missing components. A deleted truck cannot pass a real emissions test. Some tuners claim to have "hidden" codes, but this does not fool the test — it only delays detection.