6.6L Duramax L5P Silverado 5500 HD Cat Delete Downpipe 2020 Chevrolet 3.5" Stainless Steel

3.5" Catless Downpipe For 2017-2025 Duramax L5P Silverado/Sierra 2500 3500 HD

This 3.5-inch Catless Downpipe is specifically designed for 2017-2025 6.6L L5P Duramax diesel models to replace the restrictive factory downpipe.

The OEM L5P downpipe causes massive exhaust backpressure and heat buildup due to its dense catalytic converter, restricting the V8 engine's breathing. By removing the catalytic converter and utilizing a smooth, large-diameter exhaust path, this product helps reduce exhaust resistance and improve flow, resulting in faster turbo response, smoother power output, and more direct driving feedback.

Core Advantages of This L5P Downpipe

1. Reduced Backpressure

Factory downpipes are typically narrow, flattened, and restricted by catalysts. This upgrade transforms the setup into a thicker, smoother, catalyst-free straight pipe. This straight-through design minimizes the resistance the engine faces during the exhaust stroke, ensuring unobstructed airflow.

2. Horsepower & Torque Gains

Smoother exhaust discharge helps improve boosting efficiency, making acceleration more powerful and torque output more direct. Generally, power can be increased by 10-30+ HP. For the L5P diesel engine, the displacement is large and factory restrictions are more severe, making the power gains even more significant.

3. Lower Exhaust Gas Temperature (EGT)

Heavy-duty diesel engines like the L5P are frequently used for heavy towing. The factory downpipe easily accumulates heat due to environmental designs, leading to excessively high EGTs. This 3.5-inch catless downpipe quickly channels heat away, lowering EGTs by 100°F - 200°F. This is not just about performance; it prevents turbo burnout and engine power derating caused by overheating.

4. Faster Throttle Response

By lowering exhaust backpressure, the turbo blades can spool up faster, significantly shortening turbo lag. Every time you step on the gas, the power feedback is more direct and crisp, eliminating the sluggish, muffled feeling of the factory setup.

5. Exhilarating Turbo Whistle

The L5P has a very pleasant turbo whistle. After installing the 3.5-inch catless L5P downpipe, the whistle becomes crisp and loud, greatly enhancing the mechanical feel and excitement of driving.

6. Improved Fuel Economy

Smoother exhaust means reduced engine pumping losses; the engine does not need to consume extra fuel to "push" exhaust gases through a dense catalyst. In the long run, this can provide you with approximately 3% - 5% improvement in fuel mileage.

Why Choose SuncentAuto L5P Downpipe

304 Stainless Steel

Our downpipe is crafted from 304 stainless steel, offering excellent corrosion resistance, high-temperature resistance, and structural strength. It maintains reliable durability and service life even under the high-temperature, high-humidity, and long-term use environments of diesel engines.

Catless

The catless design eliminates the exhaust restrictions caused by the factory catalytic section, making exhaust discharge more direct and smooth. It is the top choice for those pursuing track performance and off-road passion.

3.5-Inch Diameter

Compared to the factory design, which is approximately 3.0 inches with an internal catalyst, the 3.5-inch straight pipe provides a larger cross-sectional area to completely eliminate exhaust backpressure.

The Duramax L5P's engine bay is very compact, and a 4-inch exhaust pipe could easily pose a safety hazard during installation. The 3.5-inch large-diameter design achieves an ideal balance between performance and ease of installation.

Direct Fit Design

Every flange and hanger is precisely calculated. You do not need to modify the factory exhaust routing, making the installation process faster and more effortless. It is perfectly suited as an upgrade component for the original exhaust system.

What's Included

👉 This product kit includes:

• 1 × 3.5" Catless Downpipe
• 2 × Stainless Steel Clamps
• 1 × Exhaust Heat Wrap

The stainless steel clamps are used for connecting the exhaust interfaces, ensuring a sealed and stable connection. The heat wrap is used to wrap the downpipe, reducing heat dissipation into the engine bay and protecting surrounding components.

Fitment Information

• Models: 2017-2025 Chevrolet Silverado 2500/3500 HD
• Models: 2017-2025 GMC Sierra 2500/3500 HD
• Engine: 6.6L L5P Duramax Diesel V8 ONLY

Please carefully check the vehicle year, model, and engine information before purchasing.

Installation Notes

• Difficulty Level: Medium-High (Professional technician installation recommended).
• Installation Time: Approximately 2-3 hours.
• Tool Requirements: V-band clamp tools and standard socket sets required.
• Tuner Required: A compatible tuner is required to properly support the catless configuration and prevent warning lights or drivability issues.
• Note: After installation, it is recommended to check the seal of the connections and the clearance of the entire exhaust system to ensure safety and stability.

Warranty & Support

We value every user's experience and provide professional after-sales support.

If you have fitment questions before purchasing or encounter problems during installation or use, please feel free to contact the Suncent customer service team.

We support free shipping in the US and a 45-day hassle-free return service.

Important Notice

This product is for "Off-Road Use" or "Track Use" ONLY. Please confirm local emissions regulations before purchasing. Our company is not responsible for consequences resulting from improper installation or violation of regulations.