What a 2017 L5P delete kit removes from your truck

A 2017 L5P delete kit removes or disables emissions control systems from a Duramax diesel engine — specifically the diesel particulate filter (DPF) and selective catalytic reduction (SCR) system. The L5P is the engine code for the 6.6-liter Duramax diesel that Chevrolet and GMC put in heavy-duty trucks starting in 2017.

When you install a delete kit, you're physically removing the DPF (which traps soot) and the SCR (which uses diesel exhaust fluid to reduce nitrogen oxides). The kit includes new exhaust piping, a tuning file that reprograms the engine computer, and sometimes a catch can to handle crankcase vapors. The result is lower exhaust temperatures, less backpressure on the engine, and no need to refill the DEF (diesel exhaust fluid) tank.

This is a permanent modification. Once deleted, your truck will not pass emissions testing in states that require it, and you cannot easily reverse the changes without replacing the original components.

Key Takeaways

  • A delete kit removes the DPF and SCR emissions systems and includes new exhaust pipes, a tuning file, and sometimes a catch can.
  • Owners report better fuel economy, faster throttle response, and lower engine temperatures after installation.
  • Deleting your truck makes it illegal to drive on public roads in most U.S. states and will cause it to fail emissions testing.
  • Installation typically costs between $1,500 and $3,500 depending on whether you do it yourself or hire a shop, plus the cost of the kit itself.
  • You will need to source the kit from a diesel performance shop, have the engine tuned, and verify that all components fit your specific truck year and cab style.

Why owners choose to delete the L5P

Diesel truck owners delete their emissions systems for three main reasons: performance, fuel economy, and reliability. The DPF and SCR systems add weight, create backpressure that restricts airflow, and require regular maintenance — the DPF regenerates by burning off trapped soot, which uses fuel and can happen at inconvenient times.

After deletion, owners report 3 to 5 miles per gallon better fuel economy on highway driving, faster acceleration, and cooler engine temperatures under load. The truck also no longer needs DEF fluid, which costs money and can freeze in cold climates. Some owners also report that deleting reduces the frequency of expensive DPF and SCR repairs, though this benefit only applies if those systems were already failing.

The trade-off is that your truck becomes illegal to operate on public roads in most states. Federal law prohibits removing or disabling emissions equipment on any vehicle, and states enforce this through emissions testing and roadside inspections. Penalties range from fines to vehicle impoundment.

What's included in a typical delete kit

A complete L5P delete kit contains the exhaust components, tuning software, and sometimes additional hardware. The core parts are a new downpipe (which replaces the section containing the DPF), a mid-pipe, and a new muffler or resonator. Some kits include a catch can that collects oil vapors from the crankcase vent, which would otherwise be burned in the SCR system.

The tuning file is the second half of the kit. This is custom software that reprograms your engine control module (ECM) to remove all emissions-related fault codes, disable the DEF system, and adjust fuel and timing parameters to match the new exhaust setup. Without this tune, your check engine light will stay on and the truck will run in a limited mode.

Kit prices vary widely. A basic bolt-on delete with tuning runs $1,200 to $2,000. Premium kits with higher-quality piping, integrated catch cans, and custom tuning can reach $3,500 or more. You'll also need to budget for installation labor if you don't do it yourself — most diesel shops charge $500 to $1,500 for the work.

Installation and tuning requirements

Installing a delete kit requires mechanical skill and the right tools. The DPF and SCR components are bolted to the exhaust system and engine, so removal involves unbolting the old parts, installing new piping, and reconnecting everything. The job typically takes 4 to 8 hours depending on your truck's configuration and whether you're working in a lift or on jack stands.

After the physical installation, the engine must be tuned. This means connecting a laptop to your truck's OBD-II port and uploading the custom tuning file to the ECM. The tuner will also clear all existing fault codes and verify that the truck starts and runs correctly. Some shops offer dyno testing to confirm power and torque gains, though this is optional.

You need to know your truck's exact configuration before ordering a kit. The L5P engine was offered in different cab styles (regular, double, crew) and bed lengths, and some kits are designed for specific combinations. Verify the kit's compatibility with your truck year, cab, and bed before purchasing.

Legal status and emissions testing

Deleting your truck is illegal under federal Environmental Protection Agency (EPA) regulations. The Clean Air Act prohibits removing or rendering inoperative any emissions control device on any motor vehicle. This applies whether you delete for performance, reliability, or any other reason.

State enforcement varies. States with active emissions testing programs — California, New York, Massachusetts, and others — will fail your truck during inspection if the DPF and SCR are missing. Some states conduct roadside inspections and can issue citations on the spot. Penalties typically include fines ranging from $500 to $10,000, and in some cases vehicle impoundment.

If you plan to delete your truck, understand that you are accepting the legal risk. Some owners delete trucks they plan to keep off public roads or use only on private property. Others delete knowing they may face fines. This is a personal decision with legal consequences.

Finding a kit and a shop

L5P delete kits are sold by diesel performance shops, both online and locally. Major suppliers include Banks Power, EFI Live, Flo Pro, and Sinister Diesel, among others. These shops sell kits directly and also through resellers. Prices and quality vary, so compare reviews and ask other L5P owners which kits they've used.

Installation can be done at a diesel performance shop, a general diesel mechanic, or by yourself if you have the skills and tools. Performance shops that specialize in Duramax trucks are your best bet because they have experience with the L5P and can handle the tuning. A general mechanic may be able to do the bolt-on work but may not have the tuning informed.

Before committing, ask the shop or kit seller about warranty, support, and what happens if something goes wrong. Some kits come with tuning support and the ability to adjust the tune if you need to troubleshoot. Others are sold as-is with no support.

Potential issues and maintenance after deletion

Deleted trucks run hotter and produce more soot in the exhaust. This means your oil will accumulate more contaminants, so more frequent oil changes are recommended — some owners switch to 3,000-mile intervals instead of the factory 7,500-mile interval. You'll also need to monitor your catch can (if you have one) and empty it regularly to prevent oil from backing up into the engine.

Some deleted trucks experience rough idle or hesitation if the tune isn't dialed in correctly. This is usually fixable with a retune. A small number of owners report that deleting exposes other problems — a failing turbo or injector that was masked by the emissions systems — but this is not common.

If you ever want to sell your truck, disclose the deletion to potential buyers. Some buyers view it as a positive (better performance and economy), while others see it as a liability (legal risk, potential engine damage). A deleted truck will be harder to sell in states with strict emissions enforcement.

Frequently Asked Questions

Will deleting my L5P void my warranty?

Yes. Chevrolet and GMC will not cover any engine or emissions-related repairs on a deleted truck. The manufacturer considers it a modification that violates the terms of the factory warranty. Any work related to the engine, turbo, injectors, or fuel system will be your responsibility.

Can I pass emissions testing with a delete kit?

No. Emissions testing specifically checks for the presence of the DPF and SCR systems. If they're removed or disabled, your truck will fail. Some states also perform OBD-II scans that will detect the deleted tune.

How much horsepower does a delete kit add?

Most L5P delete kits add 50 to 100 horsepower and 100 to 150 pound-feet of torque, depending on the kit and tune. The exact gains depend on whether you're also upgrading the turbo, injectors, or fuel system. A basic delete alone typically yields 50 to 75 hp.

Can I install a delete kit myself?

If you have diesel engine experience, proper tools, and a lift or jack stands, yes. The bolt-on work is straightforward. The tuning requires a laptop and the tuning software, which you can do yourself or have a shop handle. Most DIY installers spend 6 to 10 hours on the job.

What's the difference between a delete kit and a tune-only option?

A tune-only option disables the emissions systems in the computer without removing the physical components. This is cheaper and less visible, but the DPF and SCR hardware are still there and can still fail. A full delete removes the components, so there's nothing left to break.