5 Of The Best Upgrades For A 6.7 Cummins

The 6.7-liter Cummins engine is among the most powerful, reliable, and versatile truck diesel engines on the market. Introduced in 2007, the 24-valve powerhouse initially produced 350 horsepower and 610 to 900 lb-ft of torque, depending on the transmission type. This was one of the best years for Cummins diesel engines, alongside the third-generation 5.9-liter, which ran from 2002 to 2007. By 2019, this engine achieved an impressive 1,000 pound-feet of torque, and the latest version of the 6.7L Cummins makes 420 horsepower and 1,075 lb-ft of torque. But even with such incredible specs, there’s always room for improvement.

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As an enthusiast who has spent years researching, writing about, and even testing various aftermarket upgrades on multiple engines, including the Cummins, I’ve seen how the right upgrades can take powerful Cummins diesel engines to the next level. My background in diesel performance and engine upgrades gives me insight into what works and what doesn’t when it comes to improving the 6.7 Cummins engine.

One reason why the 6.7L Cummins is considered a great engine is its responsiveness to modifications. Upgrading it can unlock extra horsepower, improve efficiency, or improve the overall performance sound. The right upgrades can transform the 6.7L Cummins diesel engine into an absolute beast and maximize its potential. We’ve also provided information on how these upgrades were selected, where the customer ratings came from, and how these upgrades were evaluated.

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One of the simplest and most effective upgrades for the 6.7L Cummins engine is installing an air intake. Unlike gasoline engines, diesel engines thrive on a leaner air-fuel mixture, which typically falls between the 25:1 and 40:1 ratio, depending on the engine’s operating conditions. Stock intakes are generally known to be restrictive because they’re designed with a focus on emission compliance and noise rather than increasing airflow or maximizing power. An aftermarket air intake allows more oxygen into the engine and enhances combustion, which increases horsepower, torque, and mileage.

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The Sinister Diesel Cold Air Intakewhich was designed for the 2013–2018 Dodge/Ram Cummins 6.7L, is an excellent choice. Currently priced at $479.99, this intake has earned a 4.6 out of five stars from 28 global reviewers. It’s built with precision CNC mandrel-bent aluminum tubing, which gives it a lightweight design, weighing only 6.19 pounds. It also has a reusable cotton-oiled filter that provides durability, and a powder-coated finish in the brand’s signature blue shade.

According to Sinister Diesel, the intake maintains filtration down to five microns and maximizes airflow. However, some customers noted that for the premium price, it would have been ideal if the intake came with a cleaning and oiling kit — useful for maintaining the reusable cotton filter. On the bright side, users have reported noticeable performance changes.

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Upgrading the exhaust system on the 6.7L Cummins engine is a game-changing move that increases performance and efficiency. In large production scenarios, stock exhaust systems are designed to balance noise levels, cost, and performance. While they may comply with regulatory standards, OEM exhausts can lead to inefficiencies as they don’t hone the engine’s full potential and create too much backpressure — the gases pushing back into the engine’s combustion chamber. Aftermarket exhausts, particularly the high-flow options, provide better airflow and reduce back pressure. An aftermarket downpipe can help the engine perform at its peak, and the MBRP S61340PLM Exhaust System is one of the top choices.

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The MBRP downpipe has earned high praise for its performance, and it is rated 4.7 out of five stars based on 29 reviews. Priced at $364.99, this downpipe is one of the more affordable upgrades you pair with a Cummins engine. It is built from 16-gauge heavy-duty aluminized steel, which can withstand the test of time. Also, the bolt-on installation is easy, with some users noting that it just took two hours to complete and with basic tools.

Besides boosting performance, the MBRP enhances your vehicle’s exhaust sound. Your truck will have a more aggressive and sporty tone. Customers have also commended the MBRP’s build quality and lack of downing during drives. It is also relatively lightweight, which can reduce your vehicle’s overall weight and increase performance.

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Tuning boxes are the key upgrades that help maximize the performance of the 6.7L Cummins engine without making physical modifications to it. You can fine-tune your engine to handle heavy tow loads or increase the horsepower. These tuners are a more popular option because they are easy to install, reversible, and are an affordable option compared to custom tuning. One of the best box tuners of the 6.7L Cummins is the Edge Products CTS3 Evolution Performance Tunerwhich offers a plug-and-play solution. While its current $620.95 price point puts it in the premium category, this device justifies its cost with its capabilities.

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Compared to other tuning boxes, the CTS3 stands out with its slim design. It also has a vivid 5-inch full-color capacitive touch screen, which offers a user-friendly interface with a simple menu structure. It has one of the best multi-gauge displays on the market and lets drivers monitor things like transmission temperature, exhaust gas temperature (EGT), and boost, among several other things. While the initial update process may take some time, the payoff in usability is worth it. Adding to the gauges, it also features a built-in performance meter that can be set to measure 0-60 mph times and quarter-mile runs.

I installed the CTS3 on my Uncle’s Dodge Ram 2500, and can confidently say that it’s a great 6.7 Cummins tuner. It offers improved acceleration and precise shifts. The extra power is palpable with every press of the pedal. Plus, it displays detailed parameters, which makes drives more engaging. For users looking for power delivery, the CTS3 can add up to 180 horsepower and 440 lb-ft of torque, which is enough to turn any truck into a high-performance machine. The tuner offers pre-set power levels for various scenarios, like extra torque for towing heavy loads or efficiency for daily driving situations.

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The Cummins 6.7L Stealth STR Turbo HE300VG is an awesome upgrade for drivers who want to elevate their truck’s performance. While the factory turbo is reliable, it’s known to restrict airflow and limit the engine’s potential. A good aftermarket also reduces Exhaust Gas Temperatures (EGTs) and supports increased fuel delivery for greater power. Depending on the side and design of the turbocharger, you can expect a 30–40% increase in horsepower. Sold by Calibrated Power, the Stealth STR turbo is specifically designed for the Cummins engine, and it provides enough boost for towing and high-performance scenarios.

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After upgrading to the Cummins Stealth STR Turbo, I noticed an incredible increase in performance. It provides quick spools and immediate throttle responses. Interestingly, it does a good job of keeping the EGTs low, even under heavy tow duties. However, this upgrade doesn’t come cheap. The Stealth STR Turbo costs between $3,400 and $3,744 and can be purchased right from the Calibrated Power website.

The Stealth STR Turbo features High Flow Vane (HFV) Technology and supports over 600 RWHP (wheel horsepower) with stock tuning. Compared to stock tuning, the STR Turbo provides 30% more airflow and delivers up to 40+ psi of boost, and you’ll feel the feedback every time you accelerate. To top that off, the Stealth STR Turbo HE300VG is easy to install and is reliable under various conditions.

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A lift pump is a cool upgrade for diesel engines like the 6.7L Cummins. This modification ensures the injection pump receives a steady fuel supply, which yields benefits such as increased horsepower, smooth accelerations, and better throttle response. When you upgrade the fuel system, your engine receives the right amount of fuel for high-performance scenarios. One highly recommended option is the AirDog® II-5G DF-165-5G Fuel Lift Pumpdesigned specifically for Dodge Ram Cummins models from 2005 to 2016.

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This lift pump is a robust 165 GPH solution and is ideal for moderately modified trucks. Besides increasing fuel flow, the Airdog fuel pump was designed to be quieter than most stock lift pumps, which makes it a practical and performance-driven choice. The system bypasses the factory in-tank lift pump and fuel filter housing, sending the air/vapor return to the tank for maximum functionality. It comes with a $739 price tag, which is on the high-end, but the results are worth every penny.

I found the installation of the AirDog lift pump to be straightforward with the help of a couple of online videos. But, pairing it with a bean billet sump required an additional connector. Once installed, the new system worked flawlessly. As expected, it kept the fuel rail pressure stable while ensuring smooth operation. Acceleration feels stronger, and the engine runs more efficiently under heavy loads.

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When putting together this list of upgrades, our goal was to provide reliable and well-rounded recommendations to help readers boost their 6.7 Cummins engine. For products under $500, we relied on customer reviews from Amazon. Products selected for this list had to meet certain criteria. For starters, the upgrades had to have a minimum average rating of 4.2 stars and a lot of user ratings to ensure authenticity. We then identified the common strengths and weaknesses by analyzing the feedback that customers left on each product. This allowed us to identify products that deliver value.

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For the higher-priced upgrades, such as the Airdog Fuel Lift Pump and the Cummins 6.7L Stealth STR Turbo, we relied on firsthand experience and manufacturer-provided details. These products were tested in real-world scenarios to evaluate performance, installation, and overall quality — all while focusing on how these upgrades improve horsepower, throttle feedback, and efficiency of the Cummins 6.7 engine.