Stu......its a diagnostic tool and should only be used as such....as you recommend closer to the turbo the better and this means the shorter the life of sensor....putting it say in the middle of exhaust is no good...putting it up the tail pipe in a tube is pefect as you are getting accurate readings from flat out runs plus what do you use to test CO?...A probe up the exhaust....unless you got a hole in the exhaust before the tail pipe then my method has to be the best for longevity and equal accuracy.....imo.....and sensors aint cheap to keep replacing!