i ordered a new sensor and going relocate further back
i have custom piping from down pipe all the way back never had rear o2's
It seems logical to me to put the sensor bung as close to the stock position of the S1 sensor/s as possible. maybe even the same distance from the turbo as the stock bung, just at the opposite inverse position or other acceptable angle on the exhaust pipe. Not good if they line up with each other and the flow. I suspect one of the sensors would get a bad reading because the one in front of it would be deflecting gas flow if they were very close together. just a thought really..I have no data that supports this "theory". I put my wideband sensor next to the stock S1 position on the DP at a different angle as if you were looking into the pipe. It works just fine, very responsive and I can reference it against the stock S1 sensor (mine's a factory wideband) and vice versa.
I did put my EGT sensor as close to the turbo outlet as I could though. I thought about welding in bungs(EGT) for each cylinder(1.8T) but maybe after I graduate from novice to amateur tuner as I'm not that good yet to tune individual cylinders...I wrote my first tune the other day, I had a successful flash and the car didn't blow up, so YaY for me.
I think what Phila meant when he asked why you didn't use the rear o2 bung is because chances are you deleted it in your tune and the bung is there still and not being used. Not that it's the best place to put it, but most convenient. but not for you since your custom exhaust never had them installed
