Hi: From my experience with the Bosch Blue Line range of detectors, if you have a Mounting height of between 2.2 & 2.47m and a range of up to 11m then no adjustment is required. And this has been our experience with the detectors we have fitted, you fit them & then forget them until the service is due as they are extremely reliable.
Hope this has been of some help.
Regards:Andy @ Amman Security. :D