Flowmaster 20-25 GM 2500/3500 6.6L GAS Direct Fit FlowFX Muffler
Flowmaster's® Flow FX Direct-Fit Muffler exhaust system for the 2020-2026 GM 2500HD and 3500HD trucks with the 6.6L gas engines gives you a great value packed way to help you customize your GM truck to your personality. This performance muffler system fits both 2/4 Wheel drive models and is manufactured from 409 stainless steel for years of trouble-free service and performance. Features include a 3.50-inch inlet pipe leading into a 409 stainless steel Flow FX series "straight-through" muffler for great sound and maximum performance and no drone. The muffler then connects to the factory tailpipe for a simple and effective performance upgrade. Max dyno gains of 7 hp and 5 lb-ft at the rear wheels. This results in better acceleration and towing performance. The system uses all the factory hanger locations and connections for an easy installation that you can do at home. Kits include installation instructions and all necessary hardware. Backed by Flowmaster's Lifetime Limited Warranty.
Installation InstructionsWarranty
This Part Fits:
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2020-2026 | Chevrolet | Silverado 2500 HD | Custom |
| 2020-2026 | Chevrolet | Silverado 2500 HD | High Country |
| 2020-2026 | Chevrolet | Silverado 2500 HD | LT |
| 2020-2026 | Chevrolet | Silverado 2500 HD | LTZ |
| 2020-2026 | Chevrolet | Silverado 2500 HD | WT |
| 2024-2026 | Chevrolet | Silverado 2500 HD | ZR2 |
| 2020-2026 | Chevrolet | Silverado 3500 HD | High Country |
| 2020-2026 | Chevrolet | Silverado 3500 HD | LT |
| 2020-2026 | Chevrolet | Silverado 3500 HD | LTZ |
| 2020-2026 | Chevrolet | Silverado 3500 HD | WT |
| 2020-2026 | GMC | Sierra 2500 HD | AT4 |
| 2024-2026 | GMC | Sierra 2500 HD | AT4X |
| 2020-2021 | GMC | Sierra 2500 HD | Base |
| 2020-2026 | GMC | Sierra 2500 HD | Denali |
| 2022-2026 | GMC | Sierra 2500 HD | Pro |
| 2020-2026 | GMC | Sierra 2500 HD | SLE |
| 2020-2026 | GMC | Sierra 2500 HD | SLT |
| 2020-2026 | GMC | Sierra 3500 HD | AT4 |
| 2020-2021 | GMC | Sierra 3500 HD | Base |
| 2020-2026 | GMC | Sierra 3500 HD | Denali |
| 2022-2026 | GMC | Sierra 3500 HD | Pro |
| 2020-2026 | GMC | Sierra 3500 HD | SLE |
| 2020-2026 | GMC | Sierra 3500 HD | SLT |
Processing & Shipping Overview
Processing occurs before shipping.
Most in-stock items typically process within 2–3 business days before shipment or pickup. Expedited shipping options affect transit time after an order ships and do not speed up processing.
Made-to-order, special-order, vendor drop-ship, and freight items require additional processing time before shipping. Any extended lead times will be noted on the product page when applicable.
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