Wondering Stock vs Tuned L5P Duramax horsepower? The L5P Duramax engine, which is in big GM trucks from 2017 to 2025 now, is already strong from the factory.
But if you want the most power, custom tuning can find a lot of hidden horsepower and torque. Any owner to know the difference between stock (factory) and tuned power before upgrading.
How Much Power Does a Stock L5P Have?
The L5P Duramax provides an impressive baseline for a modern diesel engine, designed to deliver massive towing capability.
| Model Year | Advertised Crank Horsepower (HP) | Advertised Crank Torque (lb-ft) | Typical Rear Wheel Horsepower (RWHP) | Typical Rear Wheel Torque (lb-ft) |
|---|---|---|---|---|
| 2017-2023 | 445 HP @ 2800 RPM | 910 lb-ft @ 1600 RPM | ~400–437 RWHP | ~840–850 lb-ft |
| 2024+ (Refresh) | 470 HP @ 2800 RPM | 975 lb-ft @ 1600 RPM | N/A (Higher than previous years) | N/A (Higher than previous years) |
Key takeaway: The power that actually hits the road is called Rear Wheel Horsepower (RWHP). It is always less than the factory's advertised power because of power lost in the truck's gears and driveshafts. The stock L5P is made for reliable, hard work and has a lot of power low down.
How Much Power Does Tuning Add?
Tuning involves modifying the Engine Control Module (ECM) and, often, the Transmission Control Module (TCM) to optimize fuel delivery, turbo pressure, and shift points. This is where the L5P truly shines, as its robust factory components can handle a substantial power increase.
Custom tuners typically offer various power levels, often with Switch-on-the-Fly (SOTF) capability, allowing the driver to change tunes instantly using factory steering wheel controls.
| Tune Level (Typical) | Approximate RWHP Gain Over Stock | Approximate RWHP Total | Primary Purpose |
|---|---|---|---|
| Heavy Tow | +30 to +40 RWHP | ~430–477 RWHP | Safe, lower Exhaust Gas Temperature (EGT) increase for max-load towing. |
| Light Tow | +80 RWHP | ~480–517 RWHP | Increased responsiveness for loads under 8,000 lbs. |
| Street/Daily | +100 RWHP | ~500–537 RWHP | Best mix of daily drivability, fuel efficiency, and performance. |
| Race/Max Effort | +150 to +200 RWHP | ~550–637 RWHP | Peak performance for drag racing or unladen fun. Not recommended for towing. |
Summary:
- Stock: About 400 HP to 437 HP at the wheels.
- Tuned: Many trucks can reach 550 HP or even more! Torque also increases a lot.
What do People Say About Stock vs. Tuned
Looking at real tests and feedback from truck owners helps us see the huge power gain.
| Tune Level (Typical) | Approximate RWHP Gain Over Stock | Approximate RWHP Total | Real-World User Feedback |
|---|---|---|---|
| Light Tow Tune | +30 to +80 RWHP | ~430–517 RWHP | "Great for heavy hauling; engine runs cooler than expected." |
| Street/Daily Tune | +100 to +125 RWHP | ~500–550 RWHP | "The pedal response is awesome. The truck feels much lighter and quicker." |
| Race/Max Effort Tune | +150 to +200 RWHP | ~550–637 RWHP | "It went from a quick truck to a race car. The torque is incredible." |
Real-Life Race Test: This YouTube video showed a race between a stock L5P and one that was Tuned and Deleted with a bigger turbo and built transmission.
The most common praise for tuning is the removal of the "dead pedal" feeling. This means the gas pedal reacts much faster, making the truck feel powerful right away.
Common Upgrades for Boosting L5P Performance
When it comes to tuning your L5P engine, there are several modifications you can make to maximize its performance. Some of the most common mods for increasing L5P horsepower and torque include:
- ECU Tuning: Remapping the engine's software can provide immediate performance gains, improving throttle response and increasing overall horsepower and torque.
- Cold Air Intake: A high-flow air intake system helps your engine breathe better, increasing power and improving fuel efficiency.
- Exhaust System Modifications: Upgrading or removing restrictive components like the Diesel Particulate Filter (DPF) can unlock more horsepower and reduce backpressure.
- Turbo Upgrades: Installing a larger turbocharger can provide more air to the engine, which increases power and overall engine performance.
These mods work together to help your L5P reach its full potential.
Spetuner Offers Exhaust System Deletions on L5P Power
One of the most effective modifications we offer at Spetuner for enhancing L5P performance is exhaust system deletion. By removing restrictive components like the Diesel Particulate Filter (DPF) and Exhaust Gas Recirculation (EGR), we help you unlock more horsepower and reduce backpressure, allowing your engine to perform at its best.
This upgrade, part of a larger tuning package, works hand-in-hand with other mods like ECU tuning and cold air intakes to maximize the potential of your L5P engine. With improved airflow, you'll experience noticeable gains in horsepower, torque, and throttle response, all while reducing engine strain and improving fuel efficiency.
Is the L5P Delete Kit Right for You? (Read This First)
If you are very serious about max power, the L5P Delete Kits remove parts that limit the engine's power, like the DPF and EGR. It’s very popular for racing and off-road truck owners.
The L5P Delete Kit allows you to:
- Unlock more horsepower by removing restrictions like the DPF and EGR.
- Increase torque, which helps with towing and overall truck performance.
- Enhance engine longevity by reducing soot buildup and improving exhaust flow.
The L5P Delete Kit risks:
- It is Illegal: In the United States and many other places, it is against the law to remove or disable emissions equipment on a vehicle used on public roads. The government (EPA) has made this very clear.
- Fines and Inspection Failure: If you get caught, you could face huge fines, and your truck will fail state inspection. Some places are cracking down heavily on this.
- Voids Warranty: Using a delete kit will immediately cancel your truck's factory warranty. If anything breaks on your engine or transmission later, you will have to pay for the repair yourself.
- Environmental Impact: Removing these parts increases pollution (like soot and smog-causing gases) coming from your truck.
If you plan to tune your truck and want to achieve the highest level of performance, the L5P Delete Kit is a great addition to your setup.
Unlocking the Full Potential of Your L5P Engine
Tuning your L5P Duramax engine is one of the best ways to get more power and improve your truck's performance. Whether you’re looking for more horsepower, better towing capacity, or just a more enjoyable ride, tuning can deliver those results.
If you want to take your L5P engine performance to the next level, don’t forget the importance of performance parts like the L5P Delete Kit. This kit will help you remove the restrictions that hold back your engine, providing you with the ultimate power upgrade.
Ready to maximize your L5P power? Explore our L5P All-in-One Delete Kit today and start seeing the difference.
Frequently Asked Questions about L5P Power & Tuning
How much power does the L5P have when it's stock?
The factory L5P engine (2017–2023) produces 445 horsepower (HP) and 910 lb-ft of torque. At the wheels, this usually translates to around 400–437 HP due to drivetrain loss.
How much power does tuning add?
A street tune typically adds 100–125 HP to the wheels. More aggressive performance tunes can add over 200 HP, pushing total output beyond 600 HP.
Does tuning increase torque too?
Yes. Tuning increases both horsepower and torque significantly, improving towing capability and making the truck feel much stronger when accelerating.
Can tuning improve fuel economy (MPG)?
Possibly. Tuning can make the engine more efficient, which may improve MPG. However, since the truck becomes more responsive and powerful, most drivers tend to accelerate harder—often resulting in no real fuel savings.
What are the most common simple upgrades for tuning?
The most popular upgrades include an ECU Tune (engine computer), TCM Tune (transmission computer), and a Cold Air Intake for better airflow and performance.
Does removing the emissions parts (Delete Kit) give more power?
Yes. Removing parts like the DPF and EGR reduces backpressure, helping the engine breathe better and produce more power and torque. ⚠️ Warning: Deleting emissions systems is illegal for on-road vehicles and will void your factory warranty.
Is the Delete Kit worth the money?
For Off-Road/Race Trucks: Yes — it’s the best option for maximum performance if the truck is used strictly for racing or off-road use.
For Daily Drivers: No — the legal and warranty risks are too high. Legal tuning alone can still achieve excellent power and drivability.
