What is the JB4?

The JB4 is a plug and play tune for your turbocharged BMW. We recommend it as the starting place for all those new to modifying their car and those who plan to continue. The tuner installs between your car's sensors and it's ECU (Computer) and manipulates how the car runs via these connections. With these connections and it's own powerful computer, the JB4 adds loads of horsepower and offers so much more. For an affordable price, minimal install time, and a host of features there's not a better solution for power.