Power gains up to 100whp on pump gas

This quick install plug and play tuner connects to two easy to reach plugs on top of the C43/GLC/C63S AMG 2.0L 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: Grab our all-new JB4 PRO smartphone connection to wirelessly connect the JB4 BMW 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 info on how to use the JB4PRO free app click here.

JB4 FEATURES & BENEFITS

• Power gains up to 50whp with the C43 and up to 100whp with the C63 on pump gas! And more power available with higher octanes or E85 mixes!
• Improves 0-60 times and 1/4 mile times
• Preloaded with custom JB4 Mercedes tuning software and up to 8 maps for various fuel and modification levels
• Ethanol (E85) compatible tuning maps
• Able to read/delete fault codes
• View and record up to 40 different gauges/engine parameters in real-time with the JB4PRO app.
• Boost by gear in 1st, 2nd, and 3rd can be controlled via the JB4PRO app for a perfect launch
• Compatible with the FREE JB4PRO for logging, tuning changes, and adjustment
• The JB4 offers a lot more performance, functionality, and safety than your average performance chip
• Quick Plug & Play Installation
• CANbus OBDII integration offering unrivaled tuning features and performance
• Improved performance over non-integrated chip tunes
• Runs as smoothly as stock, this is how your vehicle should have come from the factory
• Compatible with all driving modes
• Fuel economy unchanged during normal driving
• 91 octane fuel or better required for performance gains
• Not VIN locked and can be removed without a trace and resold down the road
• Includes the rugged JB4 billet aluminum enclosure for protection
• Designed and assembled in the USA
• 5-year warranty

Vehicle Fitment

Mercedes-Benz
• 2023+ Mercedes-Benz C43 AMG 2.0L Turbo Mild Hybrid (M139)
• 2023+ Mercedes-Benz GLC 63 AMG 2.0L Turbo Plug-In Hybrid (M139)
• 2024+ Mercedes-Benz C63S E Performance AMG 2.0L Turbo Plug-In Hybrid (M139)

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