Glad it is working and the writeup is very well done, pic is worth a thousand words.
1. Current draw from the 9500i will cause a voltage drop in the wire itself and at every connection along the way from Battery to the tap in point, so always use the lowest guage wire available.
2. Ground is a relative term. Check for ground connectivity between the selected point and the BMW official ground for jumper cables should be done. It can be different and I will not bore all with the detail.
Enjoy the result, are you going to use the suction cups or convert to some other mount ?
2011 550i Sophistograu (Dark Graphite Metallic)
Oyster/Black Dakota Leather
Driver Assistance Package
Premium Package 2
3M Crystalline Tint (40%)
LoJack for sure
Dinan Stage 1 on the shopping list