Are Jekill and Hyde exhausts street legal?

Jekill and Hyde exhaust systems are designed to meet applicable sound and emissions requirements depending on the model and market. Contact us to confirm fitment and compliance for your motorcycle.

Do Jekill and Hyde exhausts fit Harley-Davidson motorcycles?

Yes, Jekill and Hyde offers exhaust systems for many Harley-Davidson models. Fitment depends on the year, model, engine, and configuration.

How It works

HOW IT WORKs

The valve

The valve is the core of the system and the technology that makes a Dr. Jekill & Mr. Hyde® exhaust truly distinctive.

At the heart of every Dr. Jekill & Mr. Hyde® exhaust is the valve system — the component that gives the exhaust its signature versatility. Thanks to its electronically controlled design, the valve can adjust in three positions, allowing the system to shift between distinct sound characters at the push of a button. Because that adaptability is such an important part of the riding experience, the valve is engineered to perform with precision in every situation.

To achieve that consistency, the valve is milled from a solid block of metal. This construction helps resist deformation under stress while also absorbing vibration more effectively, resulting in a more stable system and a cleaner, more refined sound. The valve housing is double layered and incorporates a ball joint, helping keep resistance low throughout the heating phase so the system continues to operate smoothly as temperatures rise.

Three Modes. One System.

Dr. Jekill & Mr. Hyde® is the only exhaust manufacturer with a fully sealed valve. The valve is chemically nickel-plated, allowing the treatment to penetrate the surface of the steel for greater hardness and improved corrosion resistance. It is also welded in a way that allows exhaust gases to bypass in a controlled manner, helping create the ideal balance of sound, performance, and emissions.

A Look Inside The Exhaust

Every Dr. Jekill & Mr. Hyde® motorcycle exhaust is engineered specifically for the bike it is built for. Using simulation, prototyping, and precision tuning, each system is developed to deliver the right balance of sound, performance, and fit.

Inside the exhaust, the Modeswitch, Smartbox, servomotors, and valve system work together to control the exhaust character. This electronically adjustable exhaust lets riders move between Dr. Jekill, Dynamic, and Mr. Hyde sound modes with precision.

When the valve is open, exhaust gases flow more directly through the system to create the deep, full sound of Mr. Hyde mode. When the valve is more closed, gases are redirected through the internal chambers for a quieter and more refined Dr. Jekill character.

Dynamic mode sits between the two, delivering a balanced exhaust note with more presence while staying controlled. The result is a high-performance exhaust system that adapts to the road, the environment, and the way you ride.

Parts & Placement

Each Dr. Jekill & Mr. Hyde® exhaust system is built around a series of precision components that work together to control sound, response, and rider interaction.

Parts and placement of the Dr. Jekill and Mr. Hyde exhaust system

1

Modeswitch

The rider control used to select the desired sound mode while riding.

2

Smartbox

The electronic control unit that interprets signals and manages how the system responds.

3

Servo Motor

The component that physically adjusts the valve position with accuracy and consistency.

4

Valve

The core element inside the exhaust that changes gas flow to shape the sound character.

At the push of a button

Modeswitch

The Modeswitch gives riders direct control over the exhaust character from the handlebar. With the push of a button, the system adjusts the valve position to change the selected sound mode. Designed for everyday use, the button is weather-resistant and features a red indicator light when activated.

Electronics

Smartbox

The Smartbox is the electronic control unit at the heart of the system. By reading CAN bus signals from the motorcycle’s ECU, it monitors how the exhaust should respond in real time. It manages the interaction between the selected sound mode and the operating parameters of the bike, helping the system react smoothly, intelligently, and within the intended limits.

Electronics

Servomotors

When the rider presses the Modeswitch, the Smartbox sends a signal to the servomotors to position the valve in the selected mode. Thanks to their dual-cable operation, the servomotors can move precisely between open Mr. Hyde mode, closed Dr. Jekill mode, and the 50% open Dynamic mode. Built with heavy-duty cables and a fully waterproof seal, they are designed for strong, reliable, and durable adjustment.

Push The Button

Push 1x For
Dr. Jekill Mode

Push 1x For
Mr. Hyde Mode

Push 2x For
Dynamic Mode

Explore the character of each system and hear the difference across brands and models. These recordings offer a preview, but nothing compares to the sound and feel of the system in real life.