Replace stock ECU and lambda sensor, do some simple wiring and off you go!
 
The MAXXECU Race PNP kit will run your M54 engine weather it's stock or built! Control all the features of motorsport that you would like. The PNP Connector allows you to add sensors for supporting boost, fuel, and safety features. 
 
Built-in MAP-sensor (up to 43 psi / 3bar of boost pressure)
MDash/RealDash Android app connectivity
Superfast USB communication
High or low impedance injector support
No changes in original electronics
Direct access to 6 EGT-sensors
Selected vehicle features
Uses stock harness, easy installation
The air mass meter is removed
Controls idle valve, AC, tachometer and other instruments
Controls E-Throttle, EVAP and other valves
Full CAN bus control of the stock dash
Uses stock wideband sensor(s)