Description
The Flowmaster Flow FX Cat-Back Exhaust System for 2020–2026 GM 2500HD and 3500HD trucks equipped with the 6.6L gas engine is engineered to deliver enhanced sound, improved performance, and long-lasting durability. Designed for truck owners who want a deeper, more aggressive exhaust note without interior drone, this system offers a perfect balance of power and refinement.
Constructed from mandrel-bent 16-gauge 409 stainless steel, the Flow FX system features a 3.50-inch inlet pipe feeding into a straight-through Flow FX series muffler. This design maximizes exhaust flow while producing a strong, performance-focused tone that remains comfortable for daily driving and towing. The muffler connects to the factory tailpipe location for a clean, factory-style single side exit appearance.
With dyno-proven gains of up to 11 horsepower and 10 lb-ft of torque at the rear wheels, this cat-back system improves throttle response, acceleration, and towing capability. Installation is straightforward, utilizing factory hanger locations and connections, making it an ideal at-home upgrade. Each kit includes all necessary hardware and is backed by Flowmaster’s Lifetime Limited Warranty.
Features
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3.50-inch mandrel-bent 16-gauge 409 stainless steel tubing
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Flow FX straight-through performance muffler
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Deep, aggressive to moderate exhaust tone with no drone
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Single side exit exhaust configuration
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Dyno-tested gains up to 11 hp and 10 lb-ft at the wheels
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Improved acceleration and towing performance
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Uses factory hanger locations for easy installation
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Includes all required clamps and mounting hardware
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Maintains factory warranty
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Backed by a Lifetime Limited Warranty
Specifications
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Product Type: Cat-Back Exhaust System
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Exhaust Series: Flow FX
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Material: 409 Stainless Steel
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Main Piping Diameter: 3.50 in
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Inlet Diameter: 3.50 in
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Muffler Type: Absorption
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Muffler Body Material: 409 Stainless Steel
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Muffler Body Length: 18.00 in
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Muffler Body Shape: Oval
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Exit Style: Single Side Exit
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Exhaust Tip Quantity: 1
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Exhaust Tip Diameter: 5.00 in
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Exhaust Tip Material: 304 Stainless Steel
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Exhaust Tip Finish: Black Ceramic Coating
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Exhaust Tip Cut: Angled, Rolled Edge
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Clamps Included: Yes
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Hangers Included: Yes
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Mount Type: Uses Factory Hangers
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Sound Level: Aggressive / Moderate
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Catalytic Converter Included: No
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CARB Compliant: Yes
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California Proposition 65: Yes
Vehicle Fitment
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2020 Chevrolet Silverado 2500HD 6.6L Gas
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2021 Chevrolet Silverado 2500HD 6.6L Gas
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2022 Chevrolet Silverado 2500HD 6.6L Gas
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2023 Chevrolet Silverado 2500HD 6.6L Gas
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2024 Chevrolet Silverado 2500HD 6.6L Gas
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2025 Chevrolet Silverado 2500HD 6.6L Gas
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2026 Chevrolet Silverado 2500HD 6.6L Gas
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2020 Chevrolet Silverado 3500HD 6.6L Gas
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2021 Chevrolet Silverado 3500HD 6.6L Gas
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2022 Chevrolet Silverado 3500HD 6.6L Gas
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2023 Chevrolet Silverado 3500HD 6.6L Gas
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2024 Chevrolet Silverado 3500HD 6.6L Gas
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2025 Chevrolet Silverado 3500HD 6.6L Gas
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2026 Chevrolet Silverado 3500HD 6.6L Gas
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2020 GMC Sierra 2500HD 6.6L Gas
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2021 GMC Sierra 2500HD 6.6L Gas
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2022 GMC Sierra 2500HD 6.6L Gas
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2023 GMC Sierra 2500HD 6.6L Gas
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2024 GMC Sierra 2500HD 6.6L Gas
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2025 GMC Sierra 2500HD 6.6L Gas
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2026 GMC Sierra 2500HD 6.6L Gas
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2020 GMC Sierra 3500HD 6.6L Gas
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2021 GMC Sierra 3500HD 6.6L Gas
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2022 GMC Sierra 3500HD 6.6L Gas
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2023 GMC Sierra 3500HD 6.6L Gas
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2024 GMC Sierra 3500HD 6.6L Gas
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2025 GMC Sierra 3500HD 6.6L Gas
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2026 GMC Sierra 3500HD 6.6L Gas
Fitment Notes
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Fits 2WD and 4WD models
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Designed for 6.6L gasoline engines only
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Not compatible with diesel engines
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Does not include catalytic converters
