From all of the reading I have done, I have come to the conclusion that you need to put it where ever makes u most comfortable and know what the limitations are (max temp) according to where you have the probe placed. I need to install one in my truck and am probally going to put mine after the turbo as well. I have a few friends who have PSD's and thats where they have theres and none of them have had any problems. Just remember that max temp is about 400-600 degrees lower than if placed in the manifold. Everyone has their own opinon, and thats just my 2 cent worth.