Vance & Hines 4″ Round Twin Slash Slip-On Mufflers For Harley Touring (2017–2026)
Unleash the Deep Milwaukee-Eight Sound with Signature Twin Slash Styling
Transform the quiet factory tone of your Milwaukee-Eight (M8) bagger into an aggressive, head-turning roar with the Vance & Hines 4″ Round Twin Slash Slip-On Mufflers. Specially engineered for 2017 through 2026 Harley-Davidson Touring models, these large-body mufflers feature Vance & Hines’ signature 45-degree slash-cut end treatment. Built with full-coverage heat shields, they completely eliminate unsightly pipe blueing while filling out your saddlebag cutouts with bold, muscular style.
Made in the USA, the Twin Slash series combines a mechanical louvered core baffle design with advanced acoustic damping to deliver a rich, throaty idle and a crisp, powerful exhaust note under acceleration. Engineered as a direct bolt-on upgrade for the stock 2017+ dual-header pipes, installation takes less than an hour in your garage.
Technical Specifications & Product Details
| Feature / Metric | Product Specification | Rider Benefit |
|---|---|---|
| Brand / Manufacturer | Vance & Hines (Made in USA) | Industry-leading craftsmanship, perfect fitment, and race-proven engineering |
| Muffler Diameter | 4.0 Inches Round Body | Fills out rear saddlebag cutouts cleanly for a balanced, custom bagger stance |
| Engine Platform | Harley-Davidson Milwaukee-Eight (107ci, 114ci, 117ci, & 121ci) | Acoustically tuned to enhance the distinct sound profile of M8 engines |
| Model Compatibility | 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025, 2026 Harley Touring | 100% direct bolt-on replacement for factory Touring dual headers |
| Heat Shield Design | 220-Degree Full-Coverage Heat Shields | Completely hides inner muffler bodies and permanently guards against heat bluing |
| Finish Options | Show-Quality Chrome or Matte Black Ceramic | Resilient finish designed to withstand high exhaust heat and road grime |
| End Cut Style | Signature Twin Slash Cut | Classic 45-degree angle slash cut with nested inner/outer shield detail |
| Internal Core | Louvered Core Baffles | Enhances exhaust scavenging while delivering a deep, non-droney rumble |
M8 Performance & Powerband Engineering
Restoring Throttle Response & Exhaust Velocity
The Milwaukee-Eight engine flows significantly more air than previous generations, but restrictive stock mufflers smother both its horsepower potential and exhaust note. Vance & Hines 4″ Twin Slash mufflers feature high-velocity louvered cores that optimize exhaust backpressure. By reducing restriction, these slip-ons improve exhaust gas scavenging, giving your bagger sharper throttle response and smoother roll-on power when passing at highway speeds.
Dyno-Tested Output Gains
When installed on stock 107ci, 114ci, or 117ci Milwaukee-Eight engines, the 4″ Twin Slash mufflers deliver immediate performance improvements:
- Horsepower Increase: +4.5 to +6.0 peak HP over stock exhaust.
- Torque Boost: +5.5 ft-lbs of torque gained in the critical 2,500–3,500 RPM cruising range.
- Stage 1 Potential: Pairing these mufflers with a high-flow intake and a Vance & Hines Fuelpak FP4 yields up to a 10–12% total torque boost.
Complete Vehicle Compatibility Guide
These slip-on mufflers feature asymmetric inlet sizing specifically designed for 2017+ Harley-Davidson Touring header pipes (right-hand pipe is larger than left-hand pipe). Fits all baggers in the guide below:
Harley-Davidson Touring Family (2017–2026)
- Street Glide: FLHX, FLHXS, FLHXST, CVO FLHXSE (2017–2026)
- Road Glide: FLTRX, FLTRXS, FLTRXST, FLTRU, FLTRK, CVO FLTRXSE (2017–2026)
- Electra Glide & Ultra Classic: FLHT, FLHTC, FLHTCU, FLHTK, FLHTKL (2017–2026)
- Road King: FLHR, FLHRC, FLHRXS Road King Special (2017–2026)
- CVO Bagger Models: All M8 CVO Street Glide, Road Glide, and Limited models (2017–2026)
Step-by-Step DIY Installation Guide
Upgrading your M8 Touring model is straightforward and takes roughly 45 minutes using standard hand tools.
Required Tools & Materials
- 3/8″ Ratchet with 1/2″ and 9/16″ sockets
- Torque wrench
- Copper high-temp anti-seize
- Rubbing alcohol and a clean microfiber towel
Step 1: Stock Muffler Removal
Ensure the bike is completely cool and on a level surface or lift. Remove saddlebags for clean access to mounting hardware. Loosen the factory Torx exhaust clamps at the muffler-to-header slip joints. Remove the two rear 5/16″ mounting bolts underneath each saddlebag bracket. Gently twist and pull the factory mufflers rearward off the head pipes.
Step 2: Slip-On Installation
Apply a light layer of copper anti-seize to the header pipe ends. Slide the included heavy-duty Torca clamps over the inlets of your new Vance & Hines Twin Slash mufflers. Carefully slide each muffler onto its corresponding head pipe (note: the right-side muffler inlet is larger to match the factory M8 collector pipe).
Step 3: Alignment & Mounting
Align the top channel bracket on each muffler body with the rubber isolation mount on your frame. Loosely thread in the stock mounting bolts. Step to the rear of the motorcycle to ensure both slash-cut ends line up evenly relative to your saddlebag cutouts.
Step 4: Final Torque & Critical Cleaning
Torque the rear mounting bracket bolts to 18 ft-lbs and the front Torca collector clamps to 38–42 ft-lbs.
IMPORTANT: Thoroughly clean all chrome or matte black surfaces with rubbing alcohol before starting the engine. Any oil or fingerprints left on the metal will burn into the finish permanently upon first heat-up!
Sound Profile & ECU Tuning Recommendations
Acoustic Breakdown
The Twin Slash 4″ muffler produces a classic American V-Twin sound—noticeably deeper, louder, and punchier than factory pipes without becoming harsh or fatiguing on long highway rides.
Is Fuel Tuning Required?
- Mufflers Only: If installing these slip-ons on an otherwise stock motorcycle, tuning is optional. The stock ECU can adjust fuel trims for mild muffler changes.
- Stage 1 (Mufflers + Air Cleaner): If you combine these high-flow mufflers with an aftermarket air intake, you must tune the ECU using a tuner like the Vance & Hines Fuelpak FP4 to prevent lean engine conditions and excessive popping on deceleration.
Frequently Asked Questions
Will these slip-on mufflers fit 2017–2026 Harley Trike models?
No. Trike models (Tri Glide, Freewheeler, Road Glide 3) require specific Trike slip-on part numbers due to different mounting bracket locations and rear body overhang clearance.
Are quiet baffles available for the 4″ Twin Slash series?
Yes. Vance & Hines offers optional quiet baffles (Part #21892) that lower exhaust volume by approximately 2–3 dB while maintaining a deep, rich acoustic note.
Do these mufflers preserve the factory catalytic converter?
Yes. The factory catalytic converter on 2017–2026 Harley Touring models is located inside the head pipe collector, not in the mufflers. Installing these slip-on mufflers retains emissions compliance on stock head pipes.
Order Your Vance & Hines Twin Slash Slip-Ons Today
Upgrade your 2017–2026 Harley-Davidson Touring motorcycle with the unmatched sound, performance, and style of the Vance & Hines 4″ Twin Slash Slip-On Mufflers. Backed by full manufacturer warranty protection and fast shipping directly to your door!
