I'm no expert, but I think you'll find that installing the bung & WB sensor in the test pipe is not the greatest idea. Too much likelihood of an exhaust leak happening there which will sku your WB reading.
I installed mine near the bottom end of the DP under the car , about 1/2 way back on the flat section that connects to a catalytic convertor or test pipe. Just be sure to install the bung at 10 - 11 o'clock or 1 - 2 o'clock orientation on the pipe. This will ensure any moisture will not collect on your sensor.
I'm sure you'll find many have installed the bung / sensor near the exhaust housing.....but you might want to stretch out the distance to 18-24" from the exhaust housing or the heat could damage your sensor.
If your bung is already there at 14" from turbo, give it a try. If your WB sensor overheats & fails, there are heat sinks available that screw into the bung to aid this problem.
