check the gotech website , download the manual , it has a section on this
i had hassles getting a 4 wire sensor to read , fitted a three wire to an autoguage meter and it works.grey is signal?(cant remeber) , one is pos wired to ignition , one is neg
not accurate , but when it says lean , listen.Ask my number three ring lands!
got a fitting from a hydraulic place , used an angle grinder to grind the front of this "nut".drill and weld , fit and away you go.
from what ive seen from turbod golfs etc , this needs to be fitted as close to the turbo as possible , but not so close as to melt it