How Dr Jekill & Mr Hyde's exhaust system works -

How it works

The ultimate riding experienceDr. Jekill & Mr. Hyde | The Exhaust

The Jekill and Hyde Company gives motorcyclists the ultimate riding experience with The Exhaust: an electronically adjustable exhaust system which makes it possible to choose between different sound modes on the fly. An exhaust second to none in regards to sound, esthetics and power.

Our exhaust systems embody three distinct personalities: the Dr. Jekill mode, the Dynamic mode and the Mr. Hyde mode. By a simple push of a button a valve inside the muffler closes, opens, or opens halfway, giving your exhaust more power and sound. Our software is programmed to intervene subtly and almost imperceptibly when the parameters set by the legislation are reached. This ensures that you are street legal in all riding modes.

Dr. Jekill & Mr. Hyde | The Exhaust is a completely legal exhaust system that complies with European laws and is ECE, EG-BE and TÜV approved. We care deeply about the environment, so all of our exhaust systems are built to achieve air quality standards.

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How it works

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How it sounds


Listen and enjoy the different sound modes of Dr. Jekill & Mr. Hyde. 
Push a button to start.

Dr. Jekill Mode
Mr. Hyde mode
Dynamic Mode
  • Dr. Jekill Mode
  • Dynamic mode
  • Mr. Hyde Mode

The valve The three sound modes

Our exhaust systems embody three distinct personalities*: the Dr. Jekill mode, the dynamic mode and the Mr. Hyde mode. By a simple push of a button a valve inside the muffler closes, opens or opens halfway, giving your exhaust more power and sound. You can choose per situation whether you want to ride in the Dr. Jekill mode, dynamic mode or Mr. Hyde mode. It’s up to you.

* Blackbox systems (motorcycles without CAN bus) offer two sound modes.

Learn more

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When a Dr. Jekill & Mr. Hyde exhaust is developed for a bike, it is not just a matter of putting a muffler on and it is ready to go; our engineers have developed the perfect exhaust for your motorcycle. With computer simulations and the building of prototypes, they create an exhaust that is tailor-made for each and every bike. With all these factors coming together in our product; a Dr. Jekill & Mr. Hyde exhaust system has made a long journey from the drawing board to the finished product called The Exhaust. Take a look at the cross section of The Exhaust above to see what it looks like inside, the different parts it contains and the materials which are used.

When the valve is opened, the exhaust gases go straight through the exhaust, creating the deep rumble known from Mr. Hyde. When the valve is closed, the exhaust gases are diverted via the perforation to the side chambers of the exhaust, 

which are filled with damping. After passing through they are lead back into the exhaust and are released at the back, producing the quiet Dr. Jekill sound.

Euro 5 compliance
To make our electronically adjustable exhausts Euro 5 approved for 2 in 2 Softail models with OEM-headers (except Fat Bob 114) we developed a mandatory extender for the placing of the lambda probe. This extender is placed between the body and the end cap. This solution is an important upgrade which guarantees Euro 5 compliance.


parts & placing

The different electronic control units in our exhaust systems are the brains of our product.


Push it to control your exhaust system. Choose your riding mode. Looks and function may vary per country.


Smartbox/Blackbox/Control unit
Intelligent software unit that controls the servomotors.


These will react to the signal of the Smartbox and position the valve in the required mode.


The Exhaust
Reacting to the servomotors our patented valve system will be positioned in the required mode.


At the push of a button modeswitch

The electronically controlled and adjustable system allows riders to open and close the exhaust valve with the push of a button mounted on the handlebar. The button is fully weather-resistant and flickers a red light when activated for your convenience. 

Dr. Jekill & Mr. Hyde Smartbox

Electronics smartbox

The electronic control unit in our exhaust systems is the brain of our product. The Smartbox 2 is available for all motorcycle models equipped with canbus and is fully up to date in modern day technology. Thanks to its ability to read canbus signals coming from the motorcycle’s ECU, the Smartbox 2 makes sure you will not end up on the wrong side of the law no matter what mode you select. By committing the system to the parameters set by EU legislation, the Smartbox will seamlessly and subtly intervene if necessary. Depending on your model the Smartbox 2 will carry either Euro3, Euro4 or Euro5 ready software.


Download user manual


Can Bus

The Smartbox system is a Dr. Jekill & Mr. Hyde operating systems which fits only on Can Bus models. The system has three sound modes: Dr. Jekill Mode, Dynamic Mode and Mr. Hyde Mode.

Dr. Jekill Mode
Mr. Hyde mode
Dynamic Mode

electronics Blackbox

The Blackbox is our basic control unit and suitable for non-canbus models. The Blackbox offers 2 different sound modes: the Dr. Jekill and Mr. Hyde mode. Optionally the Blackbox can be equipped with a service switch that allows you to manually control the system. Please note: this switch is not street legal and should only be used for service, racing or demonstrational purposes.


Download User Manual


non can bus

The Blackbox system is a basic Dr. Jekill & Mr. Hyde control system for Non Can Bus models which fits on Harley Davidson and Victory motorcycles. The Blackbox has two sound modes: the Dr. Jekill mode and Mr. Hyde mode. 

Dr. Jekill Mode
Mr. Hyde mode

electronics servomotors

By pressing the modeswitch, the Smartbox or Blackbox will send a signal to our servo motors. These will react and position the valve in the required mode. Thanks to a dual-cable operation the servo motors can switch back and forth between the open Mr. Hyde mode and closed Dr. Jekill mode, or engage the 50% opened Dynamic mode. The servo motors are equipped with heavy duty cables and a 100% waterproof seal to ensure strong and durable adjusters.

more info? request a brochure

Do you want to know more about The Jekill and Hyde Company products and services for your brand? Enter your email address, choose your brand and you will immediately receive a link to the desired download in your mailbox.


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