S&S Cycle Grand National: Flat Track Performance for the Modern Touring Harley

The S&S Cycle Grand National Slip-On Mufflers for 2017-2026 Harley-Davidson Touring models—including the Road Glide, Street Glide, and Road King—are designed for riders who demand more than just a shiny set of pipes. In the modern era of the Milwaukee-Eight engine, exhaust flow and backpressure management are critical. S&S Cycle, a legendary name in V-Twin performance since 1958, utilized their extensive dyno-testing and track experience to develop a muffler that increases both horsepower and torque without triggering “check engine” lights or compromising reliability. These 4-inch diameter mufflers fill out the rear cutouts of your saddlebags perfectly, providing a symmetrical, aggressive look that tells the world your bagger is built for speed.

Internal Engineering and Sound Customization

What truly sets the Grand National apart is its sophisticated internal architecture. These mufflers are equipped with removable dB reducers, a feature that puts the rider in total control of the bike’s acoustic signature. With the reducers installed, you get a deep, sophisticated, and bass-heavy rumble that is perfect for early morning departures and long-distance touring. Once removed, the high-flow perforated baffles unleash a raw, thunderous “bark” that captures the essence of the American Flat Track circuit. The baffles are wrapped in high-density race-grade packing that resists “blow out,” ensuring your Street Glide or Road Glide maintains its signature sound for years of hard riding.

Expert Tuning & Installation Advice

As specialists in Milwaukee-Eight performance, we have found that the Grand National slip-ons are among the most balanced pipes on the market for Stage I and Stage II builds. Pro Tip: While these mufflers are 50-state legal and designed to work with the factory tune, the M8 engine runs notoriously lean to meet emissions requirements. To unlock the full torque potential of your 114, 117, or 121 V-Twin, we highly recommend a fuel tuner like the Vance & Hines Fuelpak FP4. This will richen the air-fuel mixture, helping the engine run cooler and deepening the exhaust note. Installation Note: When installing on 2017-2026 models, ensure you use new muffler clamps to guarantee a perfect seal, as the high-velocity pulses of the M8 can cause leaks in old, stretched clamps. Always wipe the finish with denatured alcohol before the first heat cycle to prevent fingerprints from staining the chrome or ceramic.

Legendary American Craftsmanship

Every S&S Cycle Grand National muffler is 100% Made in the USA in Viola, Wisconsin. The attention to detail is evident in the precision welds and the depth of the plating. Whether you are building a “blacked-out” ST performance bagger or a classic chrome-heavy cruiser, these mufflers provide the perfect blend of high-end aesthetics, massive sound depth, and dyno-proven results. For the 2017-2026 Touring owner who refuses to settle for anything less than a race-proven pedigree, the S&S Grand National is the definitive choice.

Fitment Note: Fits all 2017-2026 Touring models. Not compatible with Trike models. Re-uses factory head pipe heat shields for a seamless, integrated look.

S&S Grand National Slip-On Muffler For Harley Touring

Features:

• Race inspired Grand National black ceramic end cap
• Bolts directly to stock M8 header pipes
• High flowing baffle design with removable dB reducer
• Aggressive sound and excellent horsepower
• 50-state legal