knfeparty

I bought the 4-wire bosch O2 sensor because I plan on getting a MaxTune or something similar in the future and I wanted the advertised added accuracy of having a separate ground wire. So before I go cutting into it to splice it one my current stock setup, I wanted to know who else had done this. There are two white wires, a gray wire, and a black wire. I'm assuming that the two whites are the heater wires, the gray one is the sensor wire, and the black is ground? Any advice on where I should put the ground to right now?