Rinehart Racing HP 40 2-Into-1 Slip-On Muffler For Harley Softail (2025–2026)
High-Performance 4-Inch 2-Into-1 Acoustic & Power Upgrade for Milwaukee-Eight Softails
Unleash maximum mid-range torque, razor-sharp throttle response, and iconic sound from your factory 2-into-1 header with the Rinehart Racing HP 40 2-Into-1 Slip-On Muffler. Engineered specifically for 2025 and 2026 Harley-Davidson Softail models equipped with OEM single-sided 2-into-1 exhaust setups, the HP 40 transforms quiet stock performance into a deep, aggressive V-Twin roar.
Featuring a substantial 4-inch muffler canister paired with Rinehart’s race-proven internal baffle design, the HP 40 eliminates backpressure bottlenecks while accelerating exhaust gas velocity. Handcrafted in the USA with CNC-machined billet aluminum end caps, this performance slip-on offers a clean, muscular silhouette that blends seamlessly with modern Milwaukee-Eight cruiser lines.
Technical Specifications & Product Details
| Feature / Metric | Product Specification | Rider Benefit |
|---|---|---|
| Brand / Manufacturer | Rinehart Racing (Made in USA) | Unmatched American craftsmanship, precision fitment, and show-quality finishes |
| Exhaust Configuration | 2-Into-1 Single Outlet Slip-On Design | Engineered specifically for OEM 2-into-1 factory header pipe collector joints |
| Muffler Body Diameter | 4.0-Inch Large Bore Canister | Adds a bold, muscular stance while increasing acoustic resonance and flow volume |
| Baffle Technology | High-Flow HP 40 Performance Baffle | Optimizes backpressure to unlock horsepower and deep, throaty V-Twin sound |
| Finish Options | Show Chrome or High-Temp Black with Billet Caps | Pairs perfectly with OEM engine trim and custom chrome or darked-out styling themes |
Acoustic Tuning & Power Performance
### The HP 40 Performance Core Advantage
Factory 2-into-1 mufflers on late-model Milwaukee-Eight Softails are designed with heavy baffle packing and internal restrictions that dampen sound and trap exhaust heat. Rinehart’s HP 40 core allows exhaust pulses to expand evenly through a high-velocity perforated core. This increases engine breathing efficiency, delivering immediate roll-on power and a crisp, resonant exhaust tone that comes alive when you crack the throttle.
### Key Advantages
Vehicle Compatibility Guide
Rinehart Racing HP 40 2-Into-1 Slip-On Mufflers are engineered for direct, 100% bolt-on installation on 2025–2026 Harley-Davidson Softail models equipped with stock 2-into-1 factory header pipes:
### Compatible Harley-Davidson Softail Models (2025–2026)
- Low Rider ST: FXLRST (2025–2026)
- Low Rider S: FXLRS (2025–2026 equipped with factory 2-into-1 pipe)
- Fat Bob 114 / 117: FXFBS (2025–2026 equipped with 2-into-1 header configuration)
Fitment Note: Designed solely for models featuring a factory 2-into-1 head pipe assembly. Will not fit Softail models with dual staggered or 2-into-2 header pipes without a full header swap.
Step-by-Step DIY Installation Guide
Installing the Rinehart HP 40 2-Into-1 Slip-On Muffler on your Softail takes approximately 30 to 45 minutes using standard shop tools.
### Required Tools
- 3/8″ Drive Ratchet with 1/2″ and 9/16″ sockets
- Torx key set (T27 / T30)
- Exhaust clamp tool or combination wrenches
- Penetrating lubricant
- Clean microfiber towel
### Step 1: Removal of Factory 2-Into-1 Muffler
Ensure the motorcycle is cool and supported securely. Apply a light film of penetrating oil around the single collector joint. Unbolt the rear mounting bolts securing the stock muffler canister to the frame support bracket. Loosen the factory exhaust clamp, then gently twist and slide the stock muffler rearward off the collector pipe.
### Step 2: Prepping Clamps & Alignment
Slide a new heavy-duty barrel exhaust clamp over the inlet expander joint of your new Rinehart HP 40 muffler. Apply a small amount of anti-seize or penetrating oil to the header collector tip for smooth sliding.
### Step 3: Mounting the Rinehart HP 40
Slide the Rinehart HP 40 muffler forward onto the collector pipe outlet until fully seated. Align the rear bracket mounting points with the chassis support frame. Finger-tighten the mounting bolts, check tip clearance and alignment, then torque all hardware and clamps to factory service specifications.
Frequently Asked Questions
### Is an ECU re-tune required when installing the Rinehart HP 40 Slip-On?
No. If you are keeping the stock air intake system and original 2-into-1 header pipe, an ECU re-tune is not strictly required. However, adding a high-flow air cleaner and an aftermarket tuner will maximize total horsepower and mid-range torque output.
### Will this muffler fit a Softail with dual staggered headers?
No. The HP 40 is engineered specifically as a single slip-on unit for Softail models running a 2-into-1 factory collector system. If your Softail has dual pipes, you will need standard Rinehart 3″ or 4″ dual slip-on mufflers.
### Order Your Rinehart HP 40 2-Into-1 Slip-On Today
Give your 2025–2026 Harley-Davidson Softail the sound, horsepower, and premium billet finish it deserves. Order your **Rinehart Racing HP 40 2-Into-1 Slip-On Muffler** today with fast shipping!
