S&S Cycle Grand National Slip-On Mufflers For Harley Dyna 2008-2017

S&S Cycle Grand National: Flat Track Soul for the Twin Cam Dyna

The S&S Cycle Grand National Slip-On Mufflers for 2008-2017 Harley-Davidson Dyna models are designed for the rider who values the performance-first ethos of the “Club Style” or “Performance Bagger” movement. While the Dyna platform is legendary for its handling and raw power, the stock exhaust often masks the true character of the 96ci, 103ci, and 110ci Twin Cam engines. S&S Cycle, a name synonymous with V-Twin racing since 1958, developed the Grand National series to bring the sound and soul of American Flat Track racing to the street. Compatible with popular models like the Street Bob, Low Rider, and Wide Glide, these mufflers offer a direct bolt-on solution that transforms both the visual profile and the auditory presence of your machine.

Internal Engineering and Sound Customization

What sets the Grand National apart is its versatility. Every set comes equipped with a removable dB reducer. This allows the rider to customize the experience: leave the reducers in for a sophisticated, deep, and neighborhood-friendly rumble, or remove them to unleash a raw, high-flow roar that captures the essence of a competition-spec race bike. The internal baffles are wrapped in high-quality acoustic material, ensuring that even at high RPMs, the exhaust note remains “bass-heavy” and refined, avoiding the “tinny” rasps associated with lower-quality slip-ons. By reducing backpressure, these mufflers allow your Twin Cam engine to breathe more efficiently, resulting in sharper throttle response and more aggressive acceleration throughout the powerband.

Expert Tuning & Installation Advice

As experts in the Dyna performance market, we’ve found the Grand National slip-ons to be one of the best “Stage 1” upgrades available. Pro Tip: While these are designed as a bolt-on part, 2008-2017 EFI Dynas run notoriously lean from the factory. To ensure your engine runs at its coolest and most efficient temperature, we highly recommend a fuel tuner like the Vance & Hines Fuelpak FP3. This is especially important if you have also installed a high-flow air cleaner. Installation Note: When mounting on 2008-2017 models, check the condition of your muffler-to-header gaskets (interconnect gaskets). If they appear frayed or flattened, replace them to ensure a leak-free seal. Always wipe the chrome or black finish down with denatured alcohol before the first start to remove any skin oils, which can permanently etch into the finish once the pipes heat-cycle.

American-Made Racing Heritage

Every S&S Cycle Grand National muffler is 100% Made in the USA. The attention to detail is evident in the precision welds and the depth of the finish, which is designed to withstand the intense heat cycles of an air-cooled V-Twin without discoloring. Whether you are building a “blacked-out” canyon carver or a classic chrome cruiser, the S&S Grand National Slip-Ons provide the perfect blend of high-end aesthetics, thunderous sound, and dyno-proven engineering. It is the definitive choice for the Dyna owner who refuses to settle for anything less than a race-proven pedigree.

Fitment Note: Fits 2008-2017 Dyna models. Note: Some models may require the re-use of factory mounting hardware. Not compatible with FLD Switchback factory saddlebags without minor adjustment.

S&S Grand National Slip-On Mufflers For Harley Dyna

Features:

• Up to 17% more horsepower and 9% more torque (when used with Stealth Air Cleaner Kit)
• Race-inspired design
• Stainless Steel perforated baffle design with removable dB reducer (J2825 compliant)
• Deep performance rumble