I fitted mine where the original lambda sensor went.

 

i've read on different forum that it's better to fit it a bit further from the stock location to have an accurate and reliable result.
I'm a bit confused, can't make a decision

 

Generally speaking you want it a little further away, to prolong the life of the sensor.

However the sensors aren't very expensive.

 

Optimum bung placement will vary from application to application, but using
the guideline below will ensure the longest sensor life with the most accurate
readings. Using a bung is the preferred method for mounting the oxygen
sensor in all applications.
• Weld the bung at least 24 inches downstream of the exhaust port
outlet (after the collector), or 24 inches after the turbocharger if so
equipped. The bung should be welded before the X or H pipe if so
equipped.
• Using a clock as reference, mount the bung between the 9:00
o’clock and 3:00 o’clock position. Welding the bung in the lower
section of the exhaust pipe can result in sensor damage caused by
condensation making contact with the sensor’s internal heating
element.
• A 1” bung (provided in the kit) will best protect the sensor. When
fully threaded, the sensor’s tip will sit flush with the exhaust pipe, this
does not adversely effect the readings.
• The bung should always be welded before the Catalytic Converter.
Welding the bung after the catalytic converter will skew the readings
toward lean. The skew in readings will vary with engine load and the
efficiency of the catalytic converter.

 

Thanks for the infos :smthumbup:mitsi: