no controversy , we are here to talk about, I think the story master and slave will serve to give a priority in the control of the management of the engine, just because being in two, and working for one agree with me that if there is a priority may not work, I repeat, if you try to read them on the bench (no bdm ) and put in the first reading the slave, the programmer tells you that it's wrong the ecu and start with the master, what can you tell this is my personal experience with this drive.