I've seen people put the IAT sensor on the intake/filter side of the turbo. As Scotty (?) said it needs to be in the actually charge tube after the intercooler or in the intake manifold itself, this way it reads actual Air temp going into the engine not cool air going into the turbo. On alot of fords the IAT is made into the Mass Air Sensor, we would add an actual sensor as stated above so we could tune properly.