This is our tried and tested tune for an E39 5 Series with an M52/M54 engine. These tunes were designed on a Dynojet dyno and tested in the real world! All OBD2 tune packages come with an OBD to USB cable and software to read and write your DME/ECU. A Windows computer is required to utilize the RK-Tunes flash software. Check FAQ section for windows device recommendation.