D&D Billet Cat Harley Exhaust for M8

$1,398.00 - $1,547.00

D&D M8 Billet Cat 2:1 Exhaust System for 2017–2022 Harley Milwaukee-Eight

Looking for a serious performance upgrade for your 2017–2022 Harley Milwaukee-Eight? The D&D M8 Billet Cat 2:1 Exhaust System is purpose-built to unlock the true potential of your M8 motor. Designed and engineered by D&D Performance Exhaust, this system delivers the low-end torque, mid-range punch, and top-end horsepower riders demand from a performance-driven exhaust.

Whether you’re running a stock 107/114 or a fully built Stage 4 117/124+, this system is engineered to give your bike stronger throttle response and an aggressive, race-inspired tone to match.

Engineered Specifically for the Milwaukee-Eight

This new 2:1 system is designed exclusively for Harley’s Milwaukee-Eight platform (2017–2022 models).

What’s Included:

Full M8 Billet Cat exhaust system
Heat shields
Exhaust gaskets
Complete bolt kit
Installed performance baffle
18mm O₂ bungs with 12mm inserts (for 12mm sensors)

Every component is crafted to improve exhaust flow efficiency—helping increase low-end torque and overall horsepower across the RPM range.

Choose Your Baffle: Performance or Pure Volume

The M8 Billet Cat gives you two baffle options so you can match your build and riding style.

Vortex Wrapped Baffle (2½" Core)

Best for stock displacement engines up to 114”
Balanced performance and tone
Strong low-end torque
Ideal for mildly modified setups

This is the go-to option for riders wanting maximum rideability with excellent torque gains and a refined performance sound.

Big Bore Baffle (All-Metal 2½" Core)

Best for Stage 4 114” & 117” and aftermarket 124”+ builds
Significant mid-to-high RPM power gains
Extremely loud, aggressive exhaust note
Designed for heavily modified engines with proper cam & tune

D&D’s Chief Engineer has seen substantial increases in mid- and high-range horsepower on built engines using the Big Bore baffle. It’s an all-metal perforated core designed for maximum flow.

⚠️ Note: This baffle is very loud. While it can sacrifice some low-end refinement, it maximizes performance in high-output applications.

Replacement baffles are available, but removal can be difficult. In some cases, purchasing the muffler housing with the baffle may be recommended. Because the Billet Cat uses an end-cap design, damage to the muffler end can prevent proper reinstallation.

Important: Any time you change baffles, the motorcycle must be re-tuned.

Important Fitment & Usage Notes

Will NOT fit with the Harley Cool Flow Fan
Bluing and discoloration are caused by improper tuning and are not covered under warranty
Designed for closed-course racing applications only
Not for use on pollution-controlled vehicles
Price Includes Desired End Cap (Please Email After Purchase with Selection)
Chrome End Cap Options:
- Chrome Straight Cut End Cap
- Chrome Fish Mouth End Cap
- Chrome Race Style End Cap
- Chrome 30° Angle Cut End Cap
Black End Cap Options:
- Black Straight Cut End Cap
- Black Fish Mouth End Cap
- Black Race Style End Cap
- Black 30° Angle Cut End Cap