S&S Cycle 4.5″ MK45 Thruster Slip-On Mufflers For Harley Touring

S&S MK45 Thruster: The Gold Standard for High-Volume Performance

The S&S Cycle 4.5″ MK45 Thruster Slip-On Mufflers represent the 2026 pinnacle of exhaust engineering for Harley-Davidson baggers. As the heavyweights of the S&S lineup, the MK45 series was created for the rider who understands that bigger is often better when it comes to exhaust scavenging and sound depth. By utilizing a massive 4.5-inch diameter shell, these mufflers create a larger expansion chamber, allowing for a deep, “thumping” exhaust note that vibrates through the asphalt. This design isn’t just about sound; the increased volume reduces backpressure, allowing your V-Twin engine to breathe more freely and produce higher torque. Whether you are cruising through the 2026 rally season or touring the coast, the MK45 delivers the secure, industrial-strength performance that has made S&S Cycle a legend in American motorcycling for over 60 years.

Precision Manufacturing and Custom Aesthetics

What sets the MK45 Thruster apart in the 2026 marketplace is the uncompromising quality of its internal components. Unlike budget mufflers that use simple glass-wrap, S&S utilizes a stainless steel internal baffle combined with a multi-layered acoustic packing material. This ensures that the deep tone you hear on day one remains consistent for the life of the muffler, without the “tinny” degradation common in lesser pipes. The CNC-machined Thruster end caps provide a sharp, modern finish that integrates perfectly with the lines of the Touring chassis and matches existing black or chrome accents. Available in show-quality chrome or high-temp black ceramic, these mufflers are designed to resist “blueing” and thermal discoloration, ensuring your bagger maintains its showroom-quality luster even after thousands of high-heat 2026 miles.

Expert Installation & Performance Advice

As specialists in V-Twin performance, we recommend the MK45 slip-ons for their exceptional build quality. Pro Tip: Due to the high-flow nature of these 4.5-inch mufflers, we highly recommend a Stage 1 ECU recalibration (such as an S&S Fuelpak or Dynojet Power Vision) to ensure your air-fuel ratio remains optimal for the 2026 season. Installation Note: These mufflers are a direct slip-on for factory head pipes; however, always inspect your muffler clamps for signs of wear before finalizing the install. Maintenance Note: To maintain the finish of your Thruster end caps, use a pH-neutral cleaner; avoid acidic chemicals which can dull the finish. Packing Tip: If you prefer a slightly more “neighbor-friendly” volume, S&S offers optional db-reducer inserts. Safety Note: Ensure all mounting hardware is torqued to factory specifications after the first heat cycle to prevent leaks and vibrations.

The Professional Choice for High-Output Bagger Exhausts

Choosing S&S Cycle 4.5″ MK45 Thruster Slip-Ons means investing in unmatched material quality and performance gains. It offers a unique combination of modern racing science and a classic, deep-toned roar that honors the heritage of the Harley-Davidson Touring family. For the rider who wants the biggest sound and the best flow for 2026, the S&S MK45 is the unmatched leader. Bolt them on, feel the torque, and ride the distance.

S&S 4.5″ MK45 Thruster Slip-On Mufflers For Harley Touring

Features:

• 4-1/2″ muffler is a great compliment for your Harley engine
• Stainless steel baffle construction with RaceTEX cartridge packing
• MK 45 slip-ons create a deep rumble and improve horsepower and torque, all while adding a unique look with styled aluminum end caps
• Includes removable dB reducer (J2825 compliant)

Product Style	AmericanV-twin Item #	Catalog Number	Store Sku	MFR. Product #	Availability
Black w/ Black Tips	42056	755-699	31960	550-0621	In Stock: Ships within 24 hours
Black w/ Chrome Tips	42055	755-698	33426	550-0622	In Stock: Ships next business day
Chrome w/ Black Tips	42054	755-695	31499	550-0619	In Stock: Ships within 24 hours
Chrome w/ Chrome Tips	42053	755-694	31402	550-0620	In Stock: Ships next business day