GM Duramax L5P 6.6L Downpipe-Back Exhaust System (2017-2025)
Type: Exhaust Systems
Let your L5P breathe the way it was meant to. Designed for 2017–2025 Chevrolet Silverado and GMC Sierra 2500HD/3500HD trucks equipped with the 6.6L Duramax L5P, this downpipe-back race exhaust system improves exhaust flow, enhances turbo response, and delivers a deep, aggressive tone built for off-road and competition applications.
For off-road and race use only.
The factory exhaust system can restrict airflow under load. This high-flow downpipe-back system replaces the restrictive rear section with mandrel-bent stainless steel tubing available in 4-inch or 5-inch configurations. The result is improved exhaust efficiency, lower backpressure, and stronger throttle response—especially during towing or performance driving.
Available Variants
- 2017–2019 GM 2500HD / 3500HD Duramax L5P
- 2020–2025 GM 2500HD / 3500HD Duramax L5P (OEM-style 4-bolt turbo flange required)
Each model generation is engineered for proper fitment and offered in 4” or 5” stainless steel configurations.
Vehicle Fitment
- 2017–2019 Chevrolet Silverado 2500HD / 3500HD 6.6L Duramax L5P
- 2017–2019 GMC Sierra 2500HD / 3500HD 6.6L Duramax L5P
- 2020–2025 Chevrolet Silverado 2500HD / 3500HD 6.6L Duramax L5P
- 2020–2025 GMC Sierra 2500HD / 3500HD 6.6L Duramax L5P
- Fits Extra Cab (EC), Crew Cab (CC), Short Box (SB), Long Box (LB), SRW & Dually configurations
Not compatible with Cab & Chassis trucks.
2020–2025 models must have OEM-style 4-bolt turbo flange.
Technical Specifications
| Material | 16-Gauge Stainless Steel |
| Tubing Diameter | 4” or 5” Mandrel-Bent |
| Configuration | Downpipe-Back, Single Side Exit |
| Finish | Natural Brushed Stainless |
| Hardware Included | Stainless Clamps, Contour-Bent Hangers, Prewelded Flanges |
| Design | Bung-Free High-Flow Race System |
Features
- Heavy-duty 16-gauge stainless steel construction
- Available in 4” or 5” diameters to suit performance goals
- Mandrel-bent tubing for smooth, unrestricted exhaust flow
- OEM-style hangers for stable alignment and factory-style mounting
- Improved flange design with stainless band clamps for secure sealing
- OEM-style 4-bolt turbo flange on 2020–2025 models
- Clean, unrestricted layout without sensor bungs
- Complete hardware package included for installation
Benefits
- Reduced exhaust restriction for stronger horsepower and torque delivery
- Lower EGTs during towing and heavy-duty use
- Quicker turbo spool and improved throttle response
- More efficient airflow for improved engine breathing
- Deep, aggressive exhaust tone suited for performance builds
- Durable stainless construction built for harsh operating conditions
Installation & Important Notes
- Direct bolt-on system using factory hanger locations.
- No cutting or welding required.
- Professional installation recommended for proper clearance and alignment.
- Must be paired with appropriate off-road race tuning.
- For off-road and competition use only. Verify local and federal regulations before installation.
Important Notes:
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Important Notices
- Off‑Road Use Only
Products sold by JS Speed are intended for off‑road use and may be illegal on public roads where emissions or pollution‑control laws apply. - Check Local Laws
Before purchasing or installing, verify all applicable local, state/provincial, and federal regulations to ensure the modification is legal in your area. - Professional Installation Recommended
These parts should be installed by qualified professional mechanics. Improper installation can cause performance issues or vehicle damage. Unless a product page explicitly states otherwise, installation instructions are not included. Components are designed for users with solid mechanical knowledge, and minor adjustments or modifications may be required for proper fitment. Returns or refunds cannot be accepted due to difficulty completing an installation or the absence of instructions. - Warranty Impact
Use of these parts may void your vehicle’s factory warranty. Confirm with your vehicle manufacturer before purchase and installation. - Limitation of Liability
JS Speed is not responsible for damage, failures, or issues arising from the use or installation of these products. - Product Images
Images are for illustration only and may differ from the actual product due to manufacturer updates or improvements. - No Performance Guarantees
While these products are designed to enhance performance, JS Speed does not guarantee specific performance results.
