Vance & Hines Backslash 450 Slip-On Mufflers For Harley Touring (2017–2026)
Bold Aggressive Backslash Styling Engineered for the Milwaukee-Eight Platform
Transform the rear profile and acoustic presence of your Milwaukee-Eight bagger with the Vance & Hines Backslash 450 Slip-On Mufflers. Designed specifically for 2017 through 2026 Harley-Davidson Touring models, the Backslash 450 features a massive 4.5-inch body finished with an eye-catching reverse angle slash cut that follows the lines of factory and aftermarket extended saddlebags. If you want a custom, aggressive stance paired with a deep V-Twin sound, the Backslash 450 delivers unrivaled style and performance.
Made in the USA, these large-diameter mufflers feature mechanical louvered core baffles acoustically tuned to eliminate harsh high-frequency rasps while releasing a deep, resonant rumble under acceleration. Designed as a direct bolt-on upgrade for factory 2017+ dual crossover headers, installation is fast and simple using basic garage hand tools.
Technical Specifications & Product Details
| Feature / Metric | Product Specification | Rider Benefit |
|---|---|---|
| Brand / Manufacturer | Vance & Hines (Made in USA) | Industry-leading durability, precision fitment, and race-proven design |
| Muffler Body Profile | 4.5-Inch Large Diameter Body | Completely fills saddlebag cutouts for a beefy, custom bagger aesthetic |
| Engine Platform | Harley-Davidson Milwaukee-Eight (107ci, 114ci, 117ci, & 121ci) | Acoustically tuned specifically for 4-valve M8 cylinder heads |
| Model Compatibility | 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025, 2026 Harley Touring | 100% direct bolt-on replacement for stock dual header collector pipes |
| End Cut Style | Signature Backslash Cut (Reverse Slash) | Aggressive 45-degree angle that flows smoothly with saddlebag angles |
| Finish Options | Show-Quality Chrome or High-Temp Matte Black Ceramic | Heavy-duty coating resists thermal discoloration and road debris damage |
| Internal Core | Maintenance-Free Louvered Core Baffles | Improves exhaust velocity while delivering a deep, non-droney tone |
Performance Engineering for Milwaukee-Eight Baggers
Scavenging Efficiency & Low-End Torque Recovery
Large-capacity 4-valve Milwaukee-Eight engines flow significant air volume, but factory mufflers choke exhaust gas velocity. The Vance & Hines Backslash 450 uses precision-engineered louvered baffles that maintain optimal backpressure at low-to-mid RPMs while allowing exhaust gases to exit freely under heavy acceleration. This scavenging effect ensures crisp throttle response and restores vital low-end torque lost to restrictive factory stock mufflers.
Dyno-Tested Power Output
Chassis dyno testing on stock 107ci, 114ci, and 117ci Milwaukee-Eight Touring models shows clear power improvements across the rev range:
- Horsepower Gains: +5.0 to +6.8 peak HP increase over factory mufflers.
- Torque Boost: +6.5 ft-lbs torque increase in the primary 2,500–3,800 RPM cruising range.
- Stage 1 Combined Output: Combining these mufflers with a high-flow intake and a Vance & Hines FP4 tuner unlocks up to a 12% total torque gain.
Complete Vehicle Compatibility Guide
The Backslash 450 slip-ons feature 2017+ M8-specific asymmetric inlet sizes (right-side pipe inlet is larger than left-side pipe inlet). 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 Harley Touring bike with Backslash 450 mufflers takes approximately 45 minutes using standard garage tools.
Required Tools & Supplies
- 3/8″ Drive Ratchet with 1/2″ and 9/16″ sockets
- Torque wrench (ft-lbs)
- High-temperature copper anti-seize compound
- Rubbing alcohol and a clean microfiber towel
Step 1: Stock Muffler Removal
Ensure the bike is completely cool and safely supported. Remove saddlebags for clear access to rear mounting hardware. Loosen the factory Torx exhaust clamps at the muffler-to-header collector pipe. Unbolt the two rear 5/16″ mounting bolts under each saddlebag bracket. Gently twist and pull the factory mufflers rearward off the head pipes.
Step 2: Preparing New Backslash 450 Mufflers
Apply a thin layer of copper high-temp anti-seize onto the expansion ends of your stock head pipes. Slide the included heavy-duty Torca exhaust clamps over the front inlets of your new Vance & Hines Backslash 450 mufflers.
Step 3: Mounting & Alignment
Slide each Backslash 450 muffler onto its corresponding head pipe (matching the larger inlet to the right-side collector). Align top channel brackets with your frame’s rubber isolation mounts. Thread in stock mounting bolts loosely. Step back to ensure both 4.5-inch backslash cuts sit level and align evenly with saddlebag cutouts.
Step 4: Final Torque & Critical Wipe-Down
Torque rear rubber isolation bracket bolts to 18 ft-lbs and front heavy-duty Torca barrel clamps to 38–42 ft-lbs.
CRITICAL WARNING: Thoroughly clean all chrome or matte black surfaces with rubbing alcohol before starting the engine. Oil or fingerprints left on the metal will bake permanently into the coating upon first heat-up!
Sound Profile & EFI Tuning Requirements
Acoustic Breakdown
The Backslash 450 delivers a rich, deep bass note—noticeably deeper and punchier than standard 4-inch mufflers. Its large expansion body dampens annoying high-pitched frequencies, giving your M8 engine an authoritative roar under throttle while keeping highway drone to a minimum.
Is Fuel Tuning Required?
- Mufflers Only: On otherwise stock motorcycles with factory air filters, an ECU tuner is optional. The factory ECM can manage minor exhaust flow changes.
- Stage 1 (Mufflers + Air Cleaner): When combining these high-flow slip-ons with a high-flow air intake, you must reflash the ECU using a tuner like the Vance & Hines Fuelpak FP4 to prevent lean running conditions and deceleration popping.
Frequently Asked Questions
Will these 4.5″ Backslash 450 mufflers fit Trike models?
No. Trike platforms (Tri Glide, Freewheeler, Road Glide 3) require dedicated Trike slip-on part numbers due to different mounting bracket alignment and rear trunk body clearance.
Do these mufflers keep the factory catalytic converter intact?
Yes. On 2017–2026 Harley Touring models, the catalytic converter is located inside the factory head pipe collector, not in the mufflers. Installing these slip-on mufflers retains factory emissions compliance.
Are quiet baffles available for the Backslash 450 series?
The Backslash 450 comes equipped with louvered core baffles engineered to deliver a deep, controlled acoustic tone without requiring separate quiet baffle inserts.
### Order Your Vance & Hines Backslash 450 Slip-Ons Today
Give your 2017–2026 Harley-Davidson Touring motorcycle an aggressive custom stance, improved torque response, and deep M8 sound. Order the Vance & Hines Backslash 450 Slip-On Mufflers today with full manufacturer warranty protection and fast US shipping!
