Got one that I fitted myself and it works just fine.
The ambiguity in the instructions is a bit of a worry.
What they really mean is that the unit should be mounted so that the face of it is square to the horizontal and the length of its body in line with the direction of travel. Tilting fore and aft is not a major problem if not over done.
The P3 has an enviable reputation, is certainly superior to some other makes and definitely more 'user friendly' than earlier designs.
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Old age and treachery will overcome youth and enthusiasm any day.......
Spent this morning fitting the new controller. Ran a wire thru the chasis frame to the 7 pin plug,pulled the cover cover off the plug, all 7 pins occupied. Then a sudden bolt of realisation hit, it was already wired for a controller. The previous owner had one fitted and I remembered the Hyundai service centre asking if I knew what this extra loom and wire tapped into the brake switch was for.As I didn't know it was disconnected. oh well, at least now I know how to remove the trims in the rear.