In this episode of Vince in Shorts, Vince breaks down the Burns Stainless NhB Milwaukee-Eight Bagger exhaust systems and how each one is engineered for specific high-performance builds.
When Burns Stainless entered the Harley-Davidson performance market, the mission was simple: Build purpose-built engineered systems for specific combinations — not one pipe forced onto every application. The NhB M8 lineup reflects that philosophy. Each system is designed around airflow science, real-world testing, and clearly defined performance goals.
CNC Port Precision: Where Power Begins
Every Burns Stainless M8 NhB system starts with a CNC-machined stub that fits precisely into the Milwaukee-Eight exhaust port. The exhaust port is the most critical section of the header. Exhaust velocity is highest here. Any turbulence or abrupt transition immediately creates drag losses.
Burns maintains velocity at the port, then strategically steps the primary. These stepped transitions serve two critical purposes:
- Maintain exhaust velocity for strong torque while reducing downstream drag losses.
- Create controlled reflection points for pressure wave tuning.
When the exhaust valve opens, a pressure pulse travels down the pipe. Properly timed negative pressure waves return during valve overlap, improving scavenging and helping initiate intake charge motion.
That’s how you broaden power across the RPM band instead of chasing a narrow peak number.
VsT System – The Optimized Performer
The Velocity Scavenging Technology (VsT) system was developed specifically for the 121 cubic inch CVO Milwaukee-Eight platform.
It uses primaries: 1-7/8” → 2” → 2-1/8”. The result is higher exhaust velocity and exceptional mid-range torque. On a stock 121 CVO with tuning, gains of 15 horsepower are common. Even on upgraded 135 cubic inch builds, the VsT has supported 190+ horsepower.
For 121–135 cubic inch combinations prioritizing responsiveness, rideability, and broad power delivery, the VsT is the correct choice.
Balanced. Efficient. Engineered
BbM System – The Heavy Hitter
The BbM mid-length megaphone is the benchmark for Milwaukee-Eight performance. It exits just ahead of the rear axle and fits under standard, CVO-extended, or chopped bags. In back-to-back testing, this configuration consistently delivers the strongest torque and peak horsepower.
The primary tubing is stepped, starting at: 2.00” → 2-1/8” → 2-1/4” to the collector.
Optimized for:
- 135+ cubic inch engines
- Builds exceeding 180 horsepower
- High-output street or drag race applications
For riders prioritizing maximum output and authority, this is the system.
An extended rear-exit version is available for those wanting reduced rider sound and longer aesthetics. While quieter, the extended system gives up some peak efficiency compared to the mid-length configuration.
If you want the hardest hit — this is it.
WtF System – ’Nuff Said
For extreme builds using ported “square port” cylinder heads — including +4 heads from Ward Performance — Burns offers the WtF system.
This configuration eliminates the factory counterbore restriction and uses flanges welded to accommodate a full 1-7/8” inside diameter that immediately matches 2” primary tubing. No choke point. No compromise.
Designed for 200+ horsepower builds, the WtF is the largest and most aggressive Milwaukee-Eight exhaust Burns produces. Unfiltered. Unrestricted.
’Nuff Said.
O₂ Sensor Flexibility and Tuning Support
All Burns M8 systems include both:
- 12mm O₂ bungs (stock ECU compatibility)
- 18mm O₂ bungs (wideband race tuning)
This allows seamless dyno tuning and future upgrades without modifying the exhaust.
Open Megaphone Option (Race Only)
A true race-only open megaphone is available. Without internal baffling, it maximizes top-end power but sacrifices mid-range torque and drivability. Intended strictly for drag racing in a narrow high-RPM band.
McP - Mid Control Performance Road Racing System
Burns also offers a dedicated road racing configuration using VST-sized tubing with mid-control clearance and canyon performance in mind. A 2.5” cylindrical muffler preserves mid-range torque while maintaining lean angle clearance. Built for aggressive street and road course riders with room for standard mid-controls set up.
Choosing the Right Milwaukee-Eight Exhaust
- 121–135 CI (under 180 HP): VsT – The Optimized Performer
- 135+ CI performance builds: BbM – The Heavy Hitter
- 200+ HP square-port race engines: WtF – ’Nuff Said
- Canyon / road race use: McP Mid-Control Performance Road Racing system
Burns Stainless does not build generic pipes.
Each NhB Milwaukee-Eight Bagger exhaust is engineered around airflow dynamics, scavenging efficiency, and measurable performance data.
Also available for M8 Softail models.
When power matters, design details matter.
