Power gains up to 100whp on pump gas

Now includes the JB4PRO adapter and free app built in! This quick install plug and play tuner connects to two easy to reach plugs on top of the 2023+ Mercedes-Benz AMG 2.0L Hybrid Turbo engine and safely increases turbocharger output by 3-6psi producing significant power and torque increases. Timing and fueling are appropriately rescaled for the increased boost and the installation is completely reversible in seconds. The JB4 is the only tuning system that includes CANbus providing dramatically improved performance and smoothness over other 2-channel tuning systems.

Wirelessly Connect to your JB4: Our all-new JB4 PRO smartphone connection is included to wirelessly connect the JB4 tuner to your Bluetooth 4.0 compatible iOS or Android device. This option allows you to record and analyze vehicle and tuning data, change JB4 performance maps, and update JB4 firmware as we release free newer versions with updates, more powerful maps, and new features under development. Our new adapter fits fully inside the JB4 enclosure for enhanced weather protection and a more streamlined look. The JB4PRO Free app features an intuitive easy-to-use interface, help buttons, and advanced log analysis tools that can estimate the performance of your car and help identify any tuning concerns.

For more information about the JB4PRO mobile app click here.

JB4 FEATURES & BENEFITS

• Power gains up to 50whp with the C43 and up to 100whp with the C63 on pump gas! • Improves 0-60 and quarter mile times.
• Includes multiple tuning maps for different fuel types.
• Quick plug and play installation.
• Supports E85 ethanol blends.
• Reads and deletes fault codes.
• Displays and logs up to 40 engine parameters.
• Boost by gear control for improved traction.
• Controls exhaust flap operation on supported vehicles.
• Compatible with the free JB4PRO app.
• Offers better performance and safety than basic chip tunes.
• Full CANbus integration.
• Runs as smoothly as stock.
• Compatible with all driving modes.
• No impact on fuel economy during normal driving.
• Requires 91 octane or better for performance gains.
• Not VIN locked and fully removable.
• Includes billet aluminum enclosure.
• Designed and assembled in the USA.
• 5-year warranty.

Vehicle Fitment

Mercedes-AMG M139 / M139l 2.0L Turbo Applications

• 2023+ Mercedes-Benz AMG C43 Sedan 2.0L Turbo Mild Hybrid / Electric Turbo (M139l)
• 2024+ Mercedes-Benz AMG GLC 43 SUV 2.0L Turbo Mild Hybrid / Electric Turbo (M139l)
• 2026+ Mercedes-Benz AMG GLC 43 Coupe 2.0L Turbo Mild Hybrid / Electric Turbo (M139l)
• 2025+ Mercedes-Benz AMG SL 43 Roadster 2.0L Turbo Mild Hybrid / Electric Turbo (M139l)
• 2025+ Mercedes-Benz AMG GT 43 Coupe 2.0L Turbo Mild Hybrid / Electric Turbo (M139l)
• 2024+ Mercedes-Benz AMG C63 SE Performance Sedan 2.0L Turbo Plug-In Hybrid (M139l)
• 2025+ Mercedes-Benz AMG GLC 63 S E Performance SUV 2.0L Turbo Plug-In Hybrid (M139l)
• 2025+ Mercedes-Benz AMG GLC 63 S E Performance Coupe 2.0L Turbo Plug-In Hybrid (M139l)

What is a JB4?

The JB4 is a plug & play tune available for turbocharged vehicles. The JB4 tuner installs between your car's sensors and its DME/ECU (computer) and manipulates vehicle performance through these connections making your vehicle much faster. While it's not the only tuning system that operates this way the JB4 separates itself from the competition with much more advanced connection points and processing including CANbus, fuel & spark control, Bluetooth to your smartphone, and a variety of innovative and advanced features not possible with any other system. BMS regularly publishes free mapping and firmware updates adding performance and features as ongoing development allows. In addition, the JB4 system is not VIN-locked to your vehicle and can quickly be removed and swapped between cars or resold at a later time. Often imitated but never duplicated the JB4 has been the gold standard in plug and play turbocharged performance tuning for over a decade and is sold in over 67 countries worldwide.

Is the JB4 a real tune?

Yes the JB4 is a real tune. By tapping into specific sensors and CANbus for real time vehicle data the JB4 is able to alter your boost, timing, AFR, and/or fuel trims, to a similar degree an ECU reflash would, but without the vehicle ever knowing its been tuned. The result is safe, smooth, and significant power and torque gains while retaining your factory safety systems and without having to unlock/flag your ECU.

DYNO RESULTS
2023 Mercedes-Benz C43 AMG - JB4 Maps 1, 2, and 4, 93 octane

DYNO RESULTS

2025 Mercedes-Benz C63S AMG E Performance dyno results