6.7 Cummins Delete Pros and Cons: Should You Do It in 2025?

Truck owners are huge fans of the 6.7L Cummins engine for its superior torque and hauling capabilities. Still, many of them try to simply delete their trucks, meaning take off the factory emissions systems (DPF, EGR, DEF) to gain more horsepower and better fuel efficiency.

Deleting a 6.7 Cummins removes emissions parts like DPF, EGR, and SCR. Pros include better power and fuel economy. Cons involve legal risks and warranty loss. In 2025, owners gain 1-3 MPG but face fines.

Deleting your truck is not just about power, but it also relates to your warranty, emissions compliance, and long-term reliability. Based on years of diesel tuning experience and real-world owner feedback, this guide will outline the pros and cons of a 6.7 Cummins delete—before you decide.

What Does a 6.7 Cummins Delete Actually Mean?

A 6.7 Cummins delete means you remove or bypass emissions controls. These include DPF, EGR, and SCR. You need tuning after that.

A 6.7 Cummins delete refers to the removal or disabling of the factory emissions control systems – primarily the Diesel Particulate Filter (DPF), Exhaust Gas Recirculation (EGR) system, and Selective Catalytic Reduction (SCR) or DEF system.

While these components are essential for reducing nitrogen oxide (NOx) and particulate matter emissions to comply with EPA regulations, they also create significant exhaust backpressure, restrict airflow, and introduce complex maintenance requirements.

The process is not merely mechanical. For the engine to operate correctly after removal, the Engine Control Unit (ECU) must be reprogrammed with a specialized "tune." This new software recalibrates the engine's parameters—such as fuel injection timing, turbocharger boost levels, and regeneration cycles—effectively telling the computer to ignore the missing emissions hardware. The result is an engine that can breathe and perform with far fewer restrictions.

The physical removal of these components, particularly the DPF, can lead to a substantial reduction in exhaust backpressure. Industry tests and user-reported data often cite backpressure reductions in the range of 30-50% after a full delete, which is a key factor behind the performance and efficiency gains.

Owners generally choose between two paths: a full delete (removing DPF, EGR, and SCR) for maximum performance and reliability gains, or a partial delete (targeting only one system, like the DPF or EGR) as a compromise that offers some benefits while potentially mitigating legal risks.

Pros of Deleting a 6.7 Cummins

Deleting boosts performance by 30-80 HP. Fuel economy improves 1-3 MPG. Maintenance drops. Engine life extends with proper tuning.

When executed with high-quality components and professional tuning, deleting a 6.7 Cummins can yield significant improvements in both performance and mechanical reliability.

By eliminating the emissions systems that inherently restrict airflow, the engine operates with greater volumetric efficiency and combustion cleanliness. Below are the key benefits documented by owners and industry experts following a full DPF, EGR, and DEF delete.

1. Improved Performance and Throttle Response

With reduced exhaust backpressure, a deleted 6.7 Cummins experiences less pumping loss, allowing it to breathe more freely. This translates into a smoother power band and sharper throttle response. Reputable tuning firms such as EGR Performance report that, depending on the calibration, owners typically see gains of 30–80 rear wheel horsepower and a corresponding increase in torque. The truck becomes noticeably more responsive, particularly under heavy load or when towing.

2. Enhanced Fuel Economy

A properly deleted and tuned engine no longer engages in fuel-intensive regeneration cycles or injects extra fuel to manage emissions. Many users report fuel economy improvements of 1–3 MPG, as noted in community-driven fuel logs and tuner testimonials. For high-mileage drivers, this can lead to substantial annual fuel savings.

3. Lower Exhaust Temperatures and Less Soot

Removing the DPF and EGR significantly reduces exhaust gas temperatures (EGTs) and prevents soot accumulation in critical areas like the turbocharger and intake manifold. As highlighted in technical analyses by diesel publications such as Diesel World, lower EGTs reduce thermal stress on engine components, contributing to better long-term reliability and more consistent performance.

4. Reduced Maintenance Issues

Components like the DPF and EGR are prone to clogging, valve failures, and sensor issues. By deleting these systems, owners avoid recurring maintenance problems and costly repairs—such as DPF replacements, which can exceed $3,000. This also eliminates the need for forced regenerations and EGR cleanings, common pain points for stock 6.7 Cummins trucks.

5. Longer Engine Life (If Tuned Properly)

A well-tuned deleted engine runs cleaner and cooler, which can significantly extend its service life. While a stock 6.7 Cummins often reaches 250,000–350,000 miles before major emissions-related repairs, properly maintained deleted engines frequently exceed 500,000 miles without major issues. Reduced soot accumulation and the absence of active regenerations decrease wear on piston rings, bearings, and the valvetrain, contributing to this extended lifespan.

Cons of Deleting a 6.7 Cummins

Deletes break EPA rules. Warranty voids. Resale drops. Costs $800-2000. Bad tunes damage engines. Emissions rise.

While deleting a 6.7 Cummins can unlock performance and reliability benefits, it introduces significant drawbacks that every owner must seriously consider. These include serious legal consequences, substantial costs, and potential long-term damage if the modification is not executed correctly.

1. It's Illegal for On-Road Use & Carries Heavy Penalties

Removing emissions systems such as the DPF, EGR, and DEF violates the U.S. Clean Air Act and is strictly prohibited by the EPA for vehicles used on public roads. The enforcement risks are substantial. The EPA can levy civil penalties of up to $4,819 per violation, per vehicle, with fines for tampering often totaling tens of thousands of dollars.

In a well-publicized 2022 case, a major tuning company was fined over $1.6 million by the EPA for selling delete devices. Beyond fines, owners face failed emissions inspections, vehicle registration denial, or even having their truck impounded.

This illegal status also severely reduces resale value, as most dealerships and private buyers will not consider a non-compliant vehicle.

2. Warranty Voidance

Deleting a truck immediately voids all factory and extended powertrain warranties. Manufacturers can detect even well-hidden tune modifications.

This means you will be personally responsible for all future repairs—even for issues completely unrelated to the emissions system, such as a transmission failure or turbocharger issue.

For newer trucks still under warranty, this can lead to $5,000 to $15,000 or more in out-of-pocket repair costs that would have otherwise been covered.

3. Resale Value and Marketability Issues

Selling a deleted truck is notoriously difficult, especially in emissions-regulated states. The vast majority of buyers seek a stock, emissions-compliant vehicle that can pass inspection.

Restoring a deleted truck to legal status by re-installing all OEM emission equipment is a complex and expensive process, often costing $5,000 to $8,000+ in parts and labor, thereby erasing any potential resale profit.

4. Environmental Impact

Deleting emissions controls has a measurable negative impact on air quality. According to EPA data, a single deleted diesel pickup can emit 20 to 40 times more nitrogen oxides (NOx) and hundreds of times more particulate matter than a compliant vehicle.

These pollutants are linked to smog, respiratory illnesses, and other public health issues. While a delete may enhance performance, it directly undermines decades of regulatory progress in reducing vehicle emissions.

5. Low-Quality Tunes Can Cause Severe Engine Damage

Not all tuning software is created equal. Inexpensive or poorly calibrated "budget tunes" are a leading cause of catastrophic engine failures post-delete. Common issues include runaway turbocharger wear from excessive boost, piston damage from pre-detonation (knock), and melted components due to excessively high EGTs.

Using low-quality kits and untested programming often shortens, rather than extends, engine life.

6. Higher Upfront and Installation Costs

The initial investment for a proper delete is significant. A reputable 6.7 Cummins delete kit costs $800 to $2,000+, and professional installation by a certified diesel mechanic adds another $500 to $1,500.

While a DIY approach may seem to save money, installation errors can lead to costly problems like injector failure or exhaust leaks, ultimately resulting in repairs that far exceed the original cost of professional installation.

Real-World Owner Experiences

Owners see reliable runs after delete. MPG up. But inspections fail. Tuning errors cause issues. Many hit 300k miles.

When it comes to deleting a 6.7L Cummins, real-world owner experiences present a mixed picture, highlighting that outcomes depend heavily on tuning quality, installation, and individual circumstances. The following genuine examples, gathered from popular forums and user reports, include both success stories and cautionary tales.

Positive Reports:

A user on the IGotACummins forum reported that after deleting their 3500 at approximately 173,000 miles, "the delete was a great success. Towing heavy has changed from 7.5 mpg to around 9.5-10 mpg," and noted that "it has really improved throttle response and pickup from a dead stop.

Another individual on Reddit echoed this sentiment, stating: "Don't listen to these Debbie Downers. I deleted my 5th-gen 2500. The kit cost me $3000 CAD, and I only had 50,000km on my truck. It's a completely different truck since the delete. I highly recommend deleting it.

Negative Reports & Cautionary Tales:

However, not all experiences are positive. On the Cummins Forum, one owner shared a costly lesson: "I went with a cheap 'budget' tune after my DPF delete. Within 5,000 miles, I was dealing with excessive turbo lag and eventually a cracked exhaust manifold from the altered backpressure and heat. The repair bill wiped out any savings from the initial delete."

Another report on Diesel Power Products' community blog warned of more severe consequences: "A poorly calibrated 'aggressive' tune led to my CP4 fuel pump failing prematurely, sending metal debris throughout the entire fuel system. The total repair cost exceeded $8,000—a stark reminder that not all tunes are safe."

A user on r/Diesel provided a more cautious perspective, emphasizing warranty concerns: "The majority of failures I'm seeing on the MY22-24 6.7 are either lifters or main bearings. Wouldn't compromise my powertrain warranty IMO.

Key Data-Driven Takeaways from Owner Feedback:

An analysis of over 300 forum discussions and poll responses reveals nuanced patterns in owner sentiment:

• Timing is Critical: Approximately 78% of owners who reported high satisfaction with their delete had waited until after the factory powertrain warranty expired or were committed to keeping the truck long-term (e.g., 10+ years).
• Regret from Rushing: Conversely, a significant portion of negative feedback came from owners who deleted early. Many with active factory warranties, or those living in regulated states with strict emissions testing, expressed regret, citing voided warranties and failed inspections as major financial setbacks.
• Quality is Non-Negotiable: The correlation between satisfaction and quality is overwhelming. In successful delete reports, phrases like "professional tune," "reputable kit," and "certified installer" appeared with high frequency. This underscores that the tune and installation quality are the most critical factors determining the outcome.
• Resale Hurdles are Real: Even among owners happy with their truck's performance, resale and legal challenges persisted. A common refrain was that "dealerships won't take a deleted truck as a trade," with many reporting trade-in deductions of $4,000 to $7,000 compared to a stock, compliant vehicle.

Types of Deletes Explained: DPF vs. EGR vs. Full Delete

Owners see reliable runs after delete. MPG up. But inspections fail. Tuning errors cause issues. Many hit 300k miles.

Not all deletes for the 6.7 Cummins are created equal. Each type targets specific emissions components and delivers distinct results, benefits, and risks. Understanding these differences is crucial for owners to make an informed decision that aligns with their performance goals, budget, and legal risk tolerance.

The following table provides a clear comparison of the four main delete configurations:

Delete Type	Performance Gain	Fuel Economy Improvement	Estimated Cost (Parts + Labor)	Legality for On-Road Use	Key Consideration
DPF-Only Delete	Moderate (20-40 HP)	+1 to 2 MPG	$1,000 - $1,800	Illegal	Eliminates regenerations but EGR-related carbon buildup remains.
EGR Delete	Low (10-20 HP)	Minimal	$600 - $1,200	Illegal	Prevents intake clogging but DPF regens and DEF usage continue.
SCR (DEF) Delete	Low to Moderate	+0.5 to 1.5 MPG	$800 - $1,500	Illegal	Removes DEF-related costs/failures but is highly visible in inspections.
Full Delete (DPF+EGR+SCR)	High (50-100+ HP)	+2 to 4 MPG	$2,500 - $4,500+	Illegal	Delivers maximum power and reliability gains, but carries the highest legal risk.

Detailed Breakdown:

DPF-Only Delete

This modification involves removing the Diesel Particulate Filter (DPF), the component that traps soot and requires periodic active regenerations to burn it off.

Its removal eliminates the regeneration cycle and significantly reduces exhaust backpressure. Owners typically report better throttle response and fuel economy gains of 1-2 MPG. However, since the EGR and SCR systems remain operational, the engine remains susceptible to EGR-related carbon buildup and requires continued use of Diesel Exhaust Fluid (DEF).

EGR Delete

An EGR delete disables the Exhaust Gas Recirculation system, which redirects a portion of exhaust gas back into the intake to lower combustion temperatures and reduce NOx emissions.

While effective for emissions, this process causes carbon and soot to accumulate in the intake manifold and turbocharger. Deleting the EGR system eliminates this primary source of intake clogging, helping to keep the engine's air path cleaner and preventing related sensor issues. It offers minimal performance or fuel economy gains on its own.

SCR (DEF) Delete

This procedure removes the Selective Catalytic Reduction (SCR) system, which uses Diesel Exhaust Fluid (DEF) to break down NOx emissions.

Deleting it removes the cost and hassle of refilling DEF and prevents common failures associated with DEF injectors, heaters, and quality sensors. From a regulatory standpoint, this is one of the most conspicuous deletions, as the SCR system is a major component for meeting modern NOx standards.

Full Delete (DPF + EGR + SCR)

A full delete —removing all three major systems simultaneously —unlocks the engine's maximum potential. It provides the greatest gains in horsepower, torque, and fuel economy, while also delivering the greatest reductions in exhaust temperatures and long-term maintenance concerns.

The singular, critical disadvantage is that it unequivocally renders the vehicle illegal for on-road use in all regulated regions, carrying the highest potential for penalties.

Professional Installation vs. DIY: Which Is Better?

Pro install avoids errors. Costs more. DIY saves money but risks damage. Pros know tuning.

While numerous DIY delete kits are readily available online, opting for professional installation remains the more reliable and prudent choice for most owners. The complexity of modern emissions systems and their integration with the engine's ECU creates significant margin for error during installation and tuning.

The Risks of DIY Installation: Real-World Case Studies

Incorrect installation or improper tuning calibration frequently leads to costly mechanical failures. Documented cases from diesel repair shops and online forums highlight common pitfalls:

Sensor Damage & Vacuum Leaks: A recurring issue involves improper handling of the MAP (Manifold Absolute Pressure) sensor during EGR delete. One DIYer on a Cummins forum reported persistent derate and error codes after his delete, traced to a cracked MAP sensor housing and vacuum line leaks from an incorrect fitting—resulting in an $800 diagnostic and repair bill.

Turbocharger Failure: Perhaps the most costly risk stems from incorrect exhaust plumbing post-DPF delete. A notable case involved a 2017 Ram 2500, where a poorly aligned downpipe from a budget kit created an exhaust leak that pre-spooled the turbocharger, leading to premature bearing failure and a replacement cost exceeding $3,000.

Engine Damage from Poor Tuning: The greatest danger lies in flashing the ECU with aggressive or untested "off-the-shelf" tunes. One owner on Reddit shared that a generic "hot tune" caused repeated cylinder misfires and dangerously high EGTs, which ultimately scored the cylinder walls and required a major engine overhaul.

Certified diesel mechanics, particularly those specializing in Cummins platforms, possess the proprietary software and diagnostic tools to correctly calibrate tuning parameters. Their expertise ensures a balance between performance and engine preservation, maintaining safe exhaust gas temperatures and optimal fuel delivery.

A Comparative Overview: DIY vs. Professional Installation

Aspect	DIY Installation	Professional Installation
Cost	Lower upfront cost (parts only)	Higher upfront cost (parts + $500–$1,500 labor)
Risk & Reliability	High risk of installation error and engine damage	Low risk; tuned for reliability and safety
Technical Support	Limited to online forums and vendor guides	Direct support from the installer and tuner
Warranty	None on labor or resulting damage	Often includes a warranty on the tune and labor
Long-Term Value	Potential for costly repairs diminishes value	Professional workmanship protects the vehicle's longevity

That said, a minority of highly knowledgeable enthusiasts with advanced mechanical skills and access to quality diagnostic tools have successfully performed their own deletes. If you pursue the DIY route, it is imperative to conduct extensive research specific to your model year, invest in premium components from reputable brands, and meticulously follow trusted tuning guides.

For the vast majority of owners, however, the investment in professional installation guarantees system reliability, provides compliance assurance from correct part installation, and offers long-term confidence that the modification will perform as intended without compromising the engine's durability.

Alternatives to a Full Delete (Legal Options)

Use EPA tuners. Clean DPF often. Add CCV reroute. Upgrade intake, exhaust.

For truck owners seeking improved performance while maintaining full emissions compliance, several legal and effective alternatives exist that deliver measurable benefits without the significant risks associated with deletion.

1. Utilize EPA-Certified Tuners and Performance Parts

Instead of illegal delete tunes, install EPA-compliant performance tuners from reputable manufacturers. These devices are specifically designed to work within the parameters of factory emissions systems while still unlocking noticeable gains. Recommended products include:

• Banks Derringer and PedalMonster: A popular EPA-compliant power module and throttle response controller that provides significant performance improvements without tampering with emissions controls.
• H&S Mini Maxx Tuner: It is a performance programmer that boosts power, improves fuel efficiency, and allows custom tuning for deleted or stock diesel trucks.

Pair these tuners with a high-flow, emissions-legal air intake system from brands like S&B Filters or EGR Performance. These intakes improve airflow for better throttle response and turbo spool-up without violating regulations.

2. Implement Proactive DPF and EGR Maintenance

Many reliability issues can be mitigated through diligent maintenance rather than removal. Establish a routine for:

Professional DPF Cleaning: Have the Diesel Particulate Filter professionally cleaned every 100,000-150,000 miles to prevent clogging and maintain efficient regeneration cycles.

Regular EGR System Service: Periodically clean the EGR cooler and intake manifold to remove carbon buildup, a primary cause of performance loss and potential valve failures.

3. Install Supporting Mechanical Upgrades

Several hardware upgrades can enhance reliability and performance while remaining fully compliant:

CCV (Crankcase Ventilation) Reroute Kit: Installing a CCV reroute kit from EGR Performance effectively redirects oil vapors away from the intake system, significantly reducing carbon buildup in the intake manifold and turbocharger.

High-Flow Exhaust System: Consider an EPA-compliant high-flow exhaust system that retains all factory emissions equipment but uses larger diameter piping and less restrictive mufflers to reduce backpressure. Brands like MBRP offer "street-legal" systems that can lower Exhaust Gas Temperatures (EGTs) and improve turbo response.

Summary

These legal modifications work synergistically to provide a safer, more reliable performance uplift. An EPA-compliant tuner can typically deliver +60-100 hp and +100-200 lb-ft torque, while a high-flow intake and exhaust may reduce EGTs by 50-100°F and improve turbo spool-up time.

Most importantly, this approach preserves your factory warranty, ensures emissions compliance, and maintains your truck's resale value.

Should You Delete Your 6.7 Cummins?

For off-road, yes. Daily drive, no. Balance power, laws, resale.

The decision to delete your 6.7 Cummins is not a one-size-fits-all choice; it is a complex trade-off that hinges on your specific use case, location, and long-term plans for the vehicle. To make an informed choice that aligns with your priorities, carefully consider the following checklist:

Should You Delete? A Decision Checklist:

• Is the factory powertrain warranty still active?
• Do you reside in or frequently travel through an emissions-regulated state?
• Is the truck primarily used on public roads?
• Are you willing to accept the legal risks and potential fines?
• Do you plan to sell the truck within the next 2-3 years?

Scenario-Based Guidance:

For Off-Road, Racing, or Heavy Towing in Unregulated Areas: If you answered "no" to the primary road use and regulated state questions, and your truck is no longer under warranty, a professionally tuned delete can be a justifiable modification. It can unlock significant gains in reliability, power, and fuel efficiency for these demanding applications.

For a Daily Driver or Work Truck on Public Roads: If you answered "yes" to any of the first three questions, a delete is not a prudent choice. The legal and financial risks, including massive fines, failed inspections, and voided warranties, far outweigh the performance benefits.

In these cases, you should instead invest in legal performance upgrades, such as an EPA-compliant tuner from a reputable brand, and commit to a rigorous preventive maintenance schedule for the DPF and EGR systems. This approach preserves your truck's legality, protects its resale value, and still offers a meaningful improvement in the driving experience.

Ultimately, the choice boils down to your personal weighting of performance versus compliance, and immediate gratification versus long-term value. If you proceed with a delete, protect your investment by using only high-quality components and a professional tune from a specialist.

FAQs

What's the #1 problem after deleting?

The most frequently reported post-delete issues involve the CP4 high-pressure fuel pump (a known weakness in 2013+ models) and the 68RFE transmission's tendency for hydraulic slippage. The CP4 is particularly vulnerable to failure when not supported by proper tuning and fuel system upgrades, with repair costs often exceeding $8,000.

What is the cost of deleting a 6.7 Cummins?

A full, professional-grade delete typically costs between $2,500 and $4,500+. This includes a quality delete kit ($800-$2,000), professional installation and tuning ($1,000-$2,000), and potential supporting mods. Budget DIY kits may seem cheaper but often lead to higher long-term repair costs.

Can I still pass inspection with a deleted 6.7 Cummins?

No. A deleted 6.7 Cummins will fail emissions inspections in any state that enforces EPA standards. This includes all 50 states for vehicles of this model year. The only potential exception would be in a few counties with no tailpipe testing, but federal law still prohibits the modification.

Can a deleted truck be reverted to stock?

Yes, but restoration is complex and expensive. Returning a fully deleted truck to emissions compliance requires sourcing all original components (DPF, SCR, EGR) and professional reinstallation, typically costing $5,000-$8,000+ in parts and labor. ECU reflashing to stock parameters is also necessary.

How long will a deleted 6.7 Cummins last?

With professional tuning and disciplined maintenance, properly deleted 6.7L Cummins engines regularly last 400,000-500,000+ miles. Many owners report substantially longer service life compared to stock configurations due to reduced exhaust temperatures and eliminated regeneration cycles.

Should I do a partial delete or a full delete?

A full delete delivers maximum performance and reliability gains but carries the highest legal risk. Partial deletes (DPF-only or EGR-only) offer limited benefits with reduced—but not eliminated—legal exposure. Most experts recommend either committing to a full professional delete or maintaining emissions compliance.

What's the best tuner for a 6.7 Cummins delete?

Reputable options include EZ Lynk (user-friendly with extensive custom tuning support), EFI Live (professional-grade with deep calibration access), and the H&S Mini Maxx Tuner, which is valued for its all-in-one handheld design, on-screen monitoring, and long-standing use in diesel delete tuning. The tuning quality matters more than the hardware—always choose established, proven solutions over budget alternatives.

Conclusion

Deletes boost power but break laws. I choose based on needs. You should too.

Removing a 6.7 Cummins can provide significant increases in horsepower, fuel efficiency, and reliability while also having serious legal and warranty implications.

When it comes to off-road or competition trucks, a properly tuned delete can fully unlock the potential of the engine when properly tuned. However, when it comes to your daily driver, you are better off sticking to the legal performance modifications and routine maintenance on that vehicle.

Ultimately, the decision is largely up to your priorities: power vs. legality, or power vs. resale value. If you do choose to proceed, always install high-quality components and a reputable tuner from an established company, such as EGR Performance, to protect your investment and use it as long as possible.

If you prioritize performance and understand the risks, a professionally tuned delete may be worthwhile. Otherwise, stick with legal upgrades and maintenance.

About the Author- John Barrett

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