Mid-USA Exhaust Port Torque Cones for Harley-Davidson Evo Twin Cam M8 & Shovelhead
Running open drag pipes or pulling baffles puts your engine at war with itself — exhaust gases that should be long gone come rushing back into the cylinder and kill the low-end response you were chasing in the first place. Drop a set of these CNC-machined torque cones into the exhaust port and restore the venturi effect that keeps combustion clean, throttle response sharp, and the bottom end pulling hard where you need it most.
Key Features
- Reduces exhaust reversion by accelerating exiting gases to create a venturi effect, preventing burned gases from re-entering the cylinder
- Restores low-end torque and eliminates flat spots caused by unbaffled or open exhaust systems
- Installs directly into the exhaust port at the head — held in place by the exhaust flange, no welding or permanent modification required
- No additional exhaust port gaskets required for installation
- CNC-machined with precisely calculated taper angles for maximum anti-reversion effect and unimpeded exhaust flow
- Two platform-specific variants available — select the correct SKU for your engine generation
- Sold in pairs
Technical Specifications
- Material: CNC-machined steel
- Outer Diameter (OD): 1-3/4″
- Smallest Taper Diameter: 1.31″ (Shovelhead variant)
- Cone Height: 1-1/4″ (Shovelhead variant)
- Exhaust Pipe Compatibility: 1-3/4″ O.D. exhaust systems
- Quantity: Sold in pairs (2 cones per kit)
- Fastening Method: Retained by exhaust flange clamp — no welding required
Fitment Notes
- Two variants are available — select the correct option for your engine platform at checkout; cone geometry differs between Shovelhead and Evolution/Twin Cam/M8 exhaust port dimensions
- Slim or copper exhaust gaskets may be required, depending on your specific exhaust system and head configuration
- Universal dimensional fitment: both variants are sized for 1-3/4″ O.D. exhaust pipes — compatible with any motorcycle, including metric cruisers and customs, running 1-3/4″ header pipes with a similar exhaust port interface
- Primarily recommended for use with open, straight, or unbaffled exhaust systems — bikes running full baffled systems with adequate back pressure built in may see minimal benefit
- Review the Fitment tab for a complete year and model breakdown before purchasing
Donald –
You may need slim or copper gaskets to fit.
steve dimmick –
Cones were well made, but did not use them. After reading a lot about them they are not worth messing with.
Daniel M. –
Just, what I need for my thunderhead exhaust for better performance!