The positioning of the sensors is in accordance with the most delicate thing natuer. The manual suggests, one could decide from the outside where the holes are to be drilled with mounted cladding. When I dismounted my bumper, I realized that the substructure specifies the position of the sensors. I have in the recesses provided drilled a very small hole from inside to outside and then to drill from outside the 26mm holes for the sensors. The brackets for the sensors are 2 parts: There is an annular outer part and a frame part of the interior is connected to the outer part of the bumper trim with a type Bayonet. The time this takes way was not available - I had to gently free up a Dremmel from the inside the way. In addition, the wall thickness of my bumper fascia was rather thick, so that this operation was quite fiddly.
Otherwise, everything went smoothly. I just followed the instructions and at the end everything worked perfectly.
The display is particularly successful - the LEDs are self explanatory.
I highly recommend this system. Technically the installation is however more for Patient / Advanced yourselfers.
I beg your indulgence for the grammar - German is my second language.