2017 - 2023 GM 6.6L L5P Duramax | Engine Tuning by PPEI.
2017 - 2023 GM 6.6L L5P Duramax | Engine Tuning by PPEI.

2017 - 2023 GM 6.6L L5P Duramax | Engine Tuning by PPEI


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PPEI’s tuning for the L5P Duramax is a game-changer for truck enthusiasts and professionals alike. Unlike traditional OEM (Original Equipment Manufacturer) tuning, PPEI focuses on delivering power where it counts - at the wheels. This approach ensures that your L5P Duramax operates with heightened efficiency and reliability, whether you’re cruising on the highway, towing heavy loads, or seeking an exhilarating driving experience. PPEI offers the best Duramax Engine Tuning for the L5P Duramax platform. Additionally PPEI is hands down the best tuning / custom tuner available when it comes to tuning any duramax, especially the L5P Duramax.

Understanding the BaselineOEMs like GM quote horsepower and torque as measured at the engine, with the L5P Duramax rated at 445 hp and 910 lb-ft of torque. PPEI, however, measures these figures at the wheel, revealing the true power delivered to the ground. For the L5P Duramax, PPEI’s baseline measurements are 437-wheel hp and 844-wheel tq, illustrating a powertrain loss from the engine to the wheels.

Focus on Efficiency and ReliabilityPPEI distinguishes itself by not just chasing peak horsepower and torque numbers. PPEI’s philosophy is grounded in achieving the most efficient balance of power, ensuring the longevity and reliability of your vehicle. This approach protects against issues ranging from poor fuel economy to severe transmission and engine failures.

Impressive Gains with PPEI’s L5P CalibrationsPPEI’s expert tuning provides up to 157-wheel horsepower and 363 lb-ft of torque over the OEM baseline. This elevates the L5P Duramax to nearly 600-wheel hp and 1200 lb-ft of torque. PPEI also offers the convenience of switching between six power levels using the factory steering wheel controls, catering to different driving needs and conditions.

PPEI L5P Power Levels Defined

  • OEM Stock: Factory horsepower and torque with a tweak to exceed the 98mph speed limiter.
  • Valet: Reduces performance by 90% for secure parking or preventing unauthorized joyrides.
  • Heavy Tow: Designed for towing over 15,000 lbs, offering improved performance and efficiency in heavy towing scenarios.
  • All-Purpose: A versatile tune providing a balance of power for various tasks, from towing to daily driving.
  • Street: A tune for the thrill-seekers, offering a substantial boost in power for an exhilarating driving experience.
  • Performance: The ultimate power setting for track use, pushing the L5P Duramax to its limits.

Why PPEI Recommends TuningPPEI emphasizes the importance of proper tuning, tailored to your vehicle's specific needs and configurations. They advocate for tuning that enhances performance while maintaining the vehicle's reliability and longevity.

Benefits of PPEI TuningPPEI’s tuning can transform your L5P Duramax, offering quicker acceleration, enhanced towing capabilities, and a more enjoyable driving experience. By choosing the right calibration for your activities, you ensure optimal performance and longevity of your truck.

Technical AspectsPPEI’s tuning focuses on the powertrain, comprising the engine and transmission. The tuning modifies the Engine Control Module (ECM) and Transmission Control Module (TCM), optimizing the vehicle's performance and efficiency.

Reliability and MaintenancePPEI’s calibrations are designed to maintain, if not enhance, the reliability of your L5P Duramax. Adhering to PPEI’s guidelines and maintaining your vehicle properly will ensure its longevity and performance.

Comparative Performance ResultsPPEI’s tuning demonstrates significant improvements in performance tests compared to the OEM stock. These include faster acceleration times, higher top speeds, and shorter distances required for acceleration, showcasing the profound impact of PPEI’s tuning on the L5P Duramax’s capabilities.

ConclusionPPEI’s tuning for the L5P Duramax is more than just an upgrade; it’s a comprehensive transformation of your truck’s capabilities. Balancing power, efficiency, and reliability, PPEI provides a service that exceeds expectations and redefines your driving experience. Whether for professional use or personal enjoyment, PPEI’s tuning ensures that your L5P Duramax operates at its absolute best.


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Who is the tuner/calibrator

PPEI, also known as Power Performance Enterprises, Inc., is led by the business owner and lead calibrator/tuner Kory Willis. PPEI began calibrating/tuning back in 2008, specializing in Diesel Performance but has since expanded into the Gas and Powersports industries. Kory and the team at PPEI have set many world records along with continuing many industry “firsts.” We take pride in knowing that Kory not only prides his work but also thoroughly enjoys setting expectations high for our team so our customers can have the best products and service in the world.

What does PPEI’s tuning do for my L5P Duramax

  • Tuning is intended to increase the horsepower (hp) and torque (tq) the engine can produce. OEM manufacturers, like GM, show vehicle hp and tq based on the amount of power produced by the engine, at the engine, which is 445 hp and 910 lb-ft of torque. 
  • PPEI, unlike the OEM, measures hp and tq at the wheel. What does that mean? – It means PPEI measures power that the vehicle produces to the ground showing the amount of powertrain loss from the engine, through the transmission, to the wheels. PPEI refers to this as the “baseline,” in this case, for the L5P Duramax, we measured 437-wheel hp and 844-wheel tq. The baseline shows a powertrain loss of 8 hp and 66 lb-ft of tq. 
  • PPEI’s primary focus when tuning or creating a calibration is focusing on the overall efficiency. Many individuals search for the most horsepower & torque and view it as the “best tuning,” however, more times than not, it’s quite the opposite. Many tuners advertise tuning based on the highest hp & tq, surpassing the threshold of efficiency. When the threshold of efficiency is overpowered, issues start showing up, which can be as minor as poor fuel economy or as significant as transmission and engine failure.
  • At PPEI, we love our performance, but we develop all calibrations around reliability, giving you peace of mind no matter the situation. Whether you’re at the dragstrip or hauling a heavy trailer across the nation, PPEI’s L5P calibrations redefine the limits and safely go beyond the OEM’s performance. 
  • PPEI’s L5P calibrations produce up to an additional 157-wheel horsepower and up to an extra 363 lb-ft of torque above the OEM baseline. PPEI’s L5P performance calibration brings the overall horsepower up to just shy of 600-wheel hp and 1200 lb-ft of torque. Furthermore, PPEI offers a seamless method to change between 6 different power levels (tunes) through the factory steering wheel. Each tune serves a specific purpose. However, some people may say, “just leave it in the highest hp and drive easy.” PPEI does not recommend that method. Here is why PPEI suggests using the proper power level for each specific driving condition.

PPEI L5P Power Levels Defined

OEM Stock

This power level is precisely what it says. This power level is the factory horsepower and torque with a single adjustment that allows you to exceed the factory speed limiter of 98mph. 

Tune 1 – Valet

PPEI’s main focus for this calibration is restricting the vehicle's performance for when you hand your keys over to the valet to park your vehicle or prevent someone from joy riding without permission. Valet mode will allow the vehicle to operate completely normal. However, PPEI has reduced the performance by 90% of the OEM Stock baseline. 

Tune 2 – Heavy Tow

This calibration was particularly designed for heavy towing. You may wonder, what is considered to be heavy? PPEI rates anything over 15,000 lbs. as heavy. The L5P Duramax is relatively strong, even in its stock condition. However, the towing performance isn’t what it could be. When towing heavy, the stock L5P noticeably struggles after 1,850 rpm, so PPEI created a solution to increase the vehicle's heavy towing performance. PPEI’s heavy tow calibration follows the baseline power curve until 1,800 rpm to retain a safe low-end power delivery. By adjusting the air and fuel supply properly, the heavy towing performance picks up where the factory performance falls off. By extending the powerband, or what we like to call “usable, efficient power,” the PPEI heavy tow calibration reaches optimal peak efficiency around 2,400 rpm, where the factory baseline begins fading off 600 rpm sooner. PPEI added a progressive 77-wheel hp and an additional 156 lb-ft of torque over the baseline, bringing the heavy tow calibration to an overall performance of 514-wheel hp and 1000 lb-ft of torque. The PPEI heavy tow tune effectively enables the vehicle to effortlessly power through any towing situation safely.

Tune 3 – All-Purpose

As straightforward as it sounds, this calibration is refined to serve a multipurpose role. The calibrators at PPEI swung away at this and knocked it out of the park for creating a one-size-fits-all, or should we say one-power-level-serves-all-purposes. Regardless of the task at hand, this “all-purpose” calibration does as it sounds. The L5P’s baseline performance showed a very apparent lack of “low-end giddy-up.” Where tune two, heavy tow, retains a factory-like power delivery until 1,800 rpm, we decided that the all-purpose calibration should be more aggressive. Like the heavy tow tune, the all-purpose calibration also produces a progressive horsepower and torque curve with the exception of when the powerband starts and ends. The solution to improving the sluggish factory performance was by introducing the powerband earlier, around 1,600 rpm. By bringing the power in earlier, we have to consider the engine and transmission vitals. One of the main factors when increasing performance is manipulating the air and fuel by monitoring the Exhaust Gas Temperature (EGT) to remain safe without exceeding the efficiency threshold. Accelerating and heavy engine loads increase EGT’s rapidly, increasing the chance of mechanical failure, meaning there must be guidelines to remain safe and reliable. So as all-purpose as possible, whether your L5P is towing your toys, hauling your utility trailer, or even just daily driving, PPEI recommends that you do not exceed a towing capacity of 15,000lbs. The all-purpose calibration has a powerband that is 600 rpm’s longer of more efficient, useable power over the baseline. The all-purpose calibration delivers a constant peak torque duration from 2,000 rpm and extending until 2,600 rpm. The all-purpose calibration increases the factory hp by 107-wheel horsepower and an additional 207-wheel lb-ft of torque, bringing the overall performance to 544-wheel horsepower and 1,051 lb-ft of torque. The all-purpose L5P calibration delivers the best all-around performance for everyday driving.

Tune 4 – Street

This development process specifically derived for the purpose of giving you a wow sensation when you press the peddle. Obviously, the wow-factor doesn’t exist from the factory as the L5P is kind of boring and rightfully so. The 10,000 lb. truck wasn’t designed in a wind tunnel for optimal aerodynamic or built to take turns on the Nürburgring, but the L5P has a heart (motor) and lungs (turbo) with an untapped potential from the factory. At PPEI, we thoroughly enjoy pushing vehicles to their limits and finding the weak link, which is why the aftermarket industry for hard parts exists. Without knowing the weak link, the automotive performance industry would be throwing darts blindfolded. But that isn’t the reason for the street calibration. The idea was how can PPEI deliver a safe and reliable calibration intended to be used with all the factory equipment without pushing those parts beyond their abilities. Like tune two, heavy tow, the street calibration almost mimics the power delivery but much more linear. Unlike the OEM baseline, which plateaus around 1,800 rpm, the street calibration doesn’t reach its peak performance until 2,500 rpm. The PPEI street calibration increases the factory hp by 125-wheel horsepower and an additional 274-wheel lb-ft of torque, bringing the overall performance to 562-wheel horsepower and 1,118 lb-ft of torque. The street calibration delivers the wow factor as if your L5P was a 3,700-pound corvette rather than its 10,000-pound self. This calibration is not intended to be used for towing as it could surpass the threshold of efficiency. 

Tune 5 – Performance

If you don’t think the street calibration is enough, we figured why not push it to the limit with the performance calibration. It was tough to gather data because it was more of a tire-slaying machine than a big diesel truck. Trying to make the tires maintain traction under 60mph was difficult when performing the 30 – 80 mph test and the 0-60 mph test. So, take that information how you want and understand that PPEI doesn’t recommend driving on-road with this calibration. This calibration is specifically designed to be used a ¼ mile at a time. PPEI highly recommends that you do not tow at all or daily drive in this calibration as it pushes the limits surpassing the efficiency threshold of the factory components. There are aftermarket hard parts that can complement the PPEI performance calibration and some preventative maintenance bolt-on’s that also increase the reliability and how often this calibration can be used. The performance calibration increases the factory hp by 157-wheel horsepower and an additional 363-wheel lb-ft of torque, bringing the overall performance to 594-wheel horsepower and 1,207 lb-ft of torque. This PPEI calibration is the highest achievable horsepower available for the L5P Duramax while retaining all factory components, and without any additional parts, this is tuning only.


Tune Position

Tune Definition 



Tune 0 (Zero)

OEM Stock

437 HP

844 lb-ft

Tune 1

Valet (90% Power Reduction)



Tune 2

Heavy Tow 

514 HP

1,000 lb-ft

Tune 3


544 HP

1,051 lb-ft

Tune 4


562 HP

1,118 lb-ft

Tune 5


594 HP

1,207 lb-ft

Why PPEI recommends tuning

  • PPEI doesn’t recommend all tuning. We only recommend proper tuning. So, you may wonder, what is proper tuning? Proper tuning means the calibration is designed specifically for the parts your vehicle may have installed. You wouldn’t want a calibration designed for racing if you need a calibration specifically for towing. You wouldn’t want a calibration from an individual or company that doesn’t have the ability to support the service you purchase. You will want tuning from a reputable calibrator who can back up and show data supporting what you purchase. PPEI recommends doing your homework, but ultimately, we recommend PPEI tuning above all else because PPEI has the team and the data to back the services you purchase.
  • From hotshot drivers to daily commuters, PPEI has everything you may need to improve the overall efficiency of how your vehicle operates in any situation. Some individuals will make claims of increased fuel economy. However, at PPEI, we claim improved fuel consumption may be achievable under specific driving conditions and driving styles. 
  • We understand at PPEI that you ended up here, reading this because you want your L5P Duramax to do something better or different than it does from the factory, and that’s precisely what we are here for. PPEI’s goal is to provide you with a service that exceeds expectations, just as our calibrations redefine how your vehicle operates in all aspects.

How does your vehicle benefit from tuning

  • You can make your L5P accelerate quicker, go faster, tow better, or simply be more enjoyable to drive. You are probably thinking, “that doesn’t really tell me how my vehicle benefits from tuning.” Well, your question is correct. There is no actual impact on your truck when using your L5P correctly, meaning when you are towing more than 15,000 lbs. use the heavy tow tune. When you are daily driving, use the all-purpose calibration. Think of your vehicle as a tool. It has an intended purpose which it helps you get somewhere or do something. In reference to tools, you aren’t going to use a hammer to change a light bulb or put air in your tire, just like you wouldn’t tow in the performance calibration. Using the wrong tool for the task at hand will create more issues than it solves. It all comes down to servicing your truck correctly. With the right tools and the right parts, your l5P Duramax will last a very long time and retain reliability. There are other preventive maintenance products that you can use and purchase from PPEI to help prolong the life of your L5P. For more info, contact PPEI here to learn more.

What can PPEI calibrate for my L5P Duramax

  • The L5P Duramax has many modules that control how the truck functions. However, PPEI only focuses on the powertrain and how it operates. The powertrain consists of the engine and transmission. The engine is controlled by the Engine Control Module (ECM) or can be referred to as the ECU meaning Engine Control Unit. This particular ECM/ECU is an E41 controller specific to the L5P Duramax. It controls all of the electrical engine components such as fuel injection, turbo functions, and other electrical accessories associated with how the engine operates. The transmission is controlled by the Transmissions Control Module (TCM) or the TCU, meaning Transmissions Control Unit. The TCM is known as the T87A, specific to the L5P Duramax controlling everything from shift point, converter lock-up, line pressure, and many other electrical parts connected to the transmission. The ECM and TCM communicate with each other at all times and even develop an adaptive memory of your specific driving style over time.

Are PPEI tunes going to affect the reliability of my L5P Duramax

  • Ideally, you would think, “If I increase the power, I will also decrease reliability.” In some cases, that is very true, primarily when the threshold of efficiency has been surpassed. Knowing how your calibrations work and what the calibration is designed for is very crucial. As long as you follow the guidelines PPEI provides, the PPEI calibrations will not reduce the reliability of your L5P Duramax. If you use the incorrect power level for the wrong task at hand, there is a much higher chance of decreasing the reliability. Reliability comes down to maintaining your truck and keeping it serviced with the correct oil, air filter, oil filter, transmission fluid, coolant, and all associated parts that are incorporated within your L5P’s powertrain.

Stock L5P Duramax Vs. PPEI Tuned L5P Duramax results

  • When explaining how tuning works, it can be challenging to express the actual difference in words without visual representation. It also helps if you can understand what you are looking at. PPEI uses a series of different tools to measure the power of each vehicle to show a gain or loss in performance. At PPEI, we use chassis and hub dynamometer, aka dyno’s, to measure overall force, such as horsepower and torque. We also use performance GPS devices to record ambient air temps, humidity, elevation, distance, acceleration, and speed, along with data logging equipment to record the actual output vs. the desired inputs. Basically, as a calibrator, you demand the vehicle to hit set points within the calibration. In some cases, the actual value may differ due to a limiter within the ECM or TCM. When these limiters are found, it helps the calibrators at PPEI improve how each vehicle operates in the tuning development process. Here are the performance test results for the L5P Duramax comparing the PPEI calibration to the OEM stock baseline calibration.

OEM Stock L5P vs. PPEI Tuned L5P 0 – 60 mph

0 – 60 mph – this test consists of a few different measurements.

Distance – total feet traveled to achieve 60 mph

Elapsed Time – how long it takes to go from 0 – 60 mph

Acceleration (g-force) – the change in velocity from 0 – 60 mph

Slope – the % of change in elevation between 0 – 60 mph

Distance – the distance traveled to achieve 60 mph is very noticeable when comparing the OEM stock L5P to the PPEI tuned L5P. While it took the OEM Stock truck 346 ft to achieve 60 mph, the same L5P with only the PPEI ECM & TCM calibration reached 60 mph 70 ft sooner for a total distance of 276 ft.

Elapsed Time – the length of time taken to travel from 0 – 60 mph is notable when reviewing the data compared between the OEM stock L5P Duramax and the PPEI tuned L5P. Like the distance test, the elapsed time test showed a very similar result. The OEM stock calibration traveled from 0 – 60 mph in 6.92 seconds, while the PPEI calibration enabled the same L5P to reach 60 mph 1.08 seconds quicker for an impressive time of 5.84 seconds. 

Acceleration – this model displays the amount of g-force exerted by both the OEM stock and PPEI tuned L5P. As both the OEM Stock calibration (in gray) and the PPEI calibration (in blue) speed from 0 – 60 mph gaining momentum, the PPEI tune continues to pull where the OEM stock calibration starts falling off around 30 mph. This indicates that the PPEI calibration maintains a more constant torque curve meaning a longer powerband throughout the acceleration test.

Slope - will always remain constant throughout all PPEI performance tests. As long as the percentage of elevation change is between -1% and 1%, PPEI will honor the results from each test. For this test, there was as much as a -0.38% slope to as little as 0.12% slope. There was less than a 1 ft change in elevation over the total distance traveled when performing this test. 

OEM Stock L5P vs. PPEI Tuned L5P 30 – 80 mph

30 – 80 mph – this test consists of a few different measurements.

Distance – total feet traveled between 30 - 80 mph

Elapsed Time – how long it takes to go from 30 – 80 mph

Acceleration (g-force) – the change in velocity from 30 – 80 mph 

Slope – the % of change in elevation between 30 – 80 mph 

Distance – the amount of ground (ft) covered when accelerating from 30 – 80 mph is worth noting because that’s an exact simulation as if you were merging with traffic, on an interstate, from the on-ramp. While the distance may seem irrelevant, not all on-ramps are the same length, which can also apply to other situations such as passing or overtaking the vehicle(s) in front of you. The OEM stock L5P calibration takes 716.3 ft to accelerate from 30 – 80 mph, while the PPEI calibration shows major improvement by accomplishing the same task 168.91 ft sooner. The PPEI calibration enables the L5P Duramax to travel from 30 – 80 mph within total distance of 547.39 ft.  which is 26.7% shorter in overall distance, which makes merging, passing, and overtaking other vehicles effortless. 

Elapsed Time – like the distance test, the duration of time between 30 – 80 mph just highlights the untapped penitential these L5P Duramax’s come with from the factory. The OEM L5P calibration can accelerate from 30 – 80 mph in 8.3 seconds where the PPEI tuned L5P does the same performance test 1.92 seconds faster. Speeding from 30 – 80 mph in 6.38 seconds, the PPEI calibration shows a substantial performance improvement over the Stock calibration.

Acceleration – where the OEM Stock L5P and the PPEI tuned L5P have different distances and elapsed times, the start and finish speeds remain constant. By looking at this model it measures g-force between the OEM stock and PPEI tuned calibration showing a constant improvement throughout the powerband when accelerating from 30 – 80 mph. 

Slope – will always remain constant throughout all PPEI performance tests. As long as the percentage of elevation change is between -1% and 1%, PPEI will honor the results from each test. For this test, there was as much as a 0.18% slope to as little as -0.05% slope. There was less than a 1 ft change in elevation over the total distance traveled when performing this test. 

OEM Stock L5P vs. PPEI Tuned L5P ¼ mile

¼ mile – this test consists of a few different measurements.

Distance – which remains constant at 1320 ft or ¼ mile.

Elapsed Time – how long it takes to reach a ¼ mile

Speed – the top speed reached over the course of a ¼ mile

Slope – the % of change in elevation over the distance of ¼ mile

¼ mile – Since the distance is predetermined, it is easier to analyze the test as a whole instead of breaking down each aspect of this performance test into individual parts. On the left, the OEM stock L5P model (in gray) shows an elapsed time of 15.06 seconds at 92 mph in the ¼ mile as our baseline performance result. The PPEI calibrated L5P model (in orange) shows a progressive improvement as the distance increases producing an additional gain of 10 mph over the OEM for a top speed of 102 mph. Where the speed increases, the elapsed time decreases by 1.02 seconds for a quicker and faster total time of 14.04 seconds. Where this performance test may be irrelevant for your specific needs, it highlights what your L5P is capable of.  

Customer Reviews

Based on 10 reviews
Josh Workman
Trust PPEI!!

Went with a different company for emissions compliant tuning at first. Couldn’t make it 250 miles while towing without going into REGEN. Fuel mileage sucked but to top it off while on vacation I had to stop and force a service REGEN. The next day I switched both ECM and TCM tunes to PPEI. Hauled 1700 miles back home with a REGEN every 650-700 miles. More power, better throttle response and overall a much happier experience. Do your research before tuning and then chose PPEI.

Daniel Ford
2021 L5P & TCM tuning makes a huge improvement

I must admit I had done one of my 2021 L5P’s with a different company first and it was a learning curve with swapping the ECM’s and then having to deal with the Vat’s system but overall was impressed with the outcome. I went with PPEI with this second one because how well I liked the TCM tune from them for that same truck and was really excited with the improvements it provided. That all being said I went with the ECM tunes SOTF option, used the E41 upgrade so I didn’t have to remove the ECM and never had any issues with the Vat’s system this go. PPEI staff is super to deal with, highly recommend them

Ethan Davis
2018 L5P

Just what I needed to wake this thing up, throttle response, torque, I feel like the engine just runs so much smoother! Support was second to none, great job by the team!

Greg Hall
A+++++ is all I can say


Warren Underhill
2022 L5P Duramax ECM & TCM

Customer service and support has been great so far and the truck feels incredible, especially with the TCM tuning as well. Great combination with both the engine and transmission tuning. This was my first time with tuning of the L5P and they walked me through the full process. Highly recommended!


PPEI, also known as Power Performance Enterprises, Inc., is led by the business owner and lead calibrator/tuner Kory Willis. PPEI began calibrating/tuning back in 2008, specializing in Diesel Performance but has since expanded into the Gas and Powersports industries. Kory and the team at PPEI have set many world records along with continuing many industry “firsts”. We take pride in knowing that Kory not only prides his work, but also thoroughly enjoys setting expectations high for our team so our customers can have the best products available in the world.