Installed mine today (car came de-badged), here are the measurements if anyone else needs them...(from the BMW TIS)
From what I could tell on other cars, the bottom left of the 1 is pretty close to inline with the right edge of the third brake light. I applied tape vertically there (not pictured) with a level to estimate where the emblem should start. Then applied the horizontal tape template right above the lip below the emblem. I used a level as you cant rely on the lip edge since it curves up as you go right
Template:
The tape is 23.5mm tall, this will put the badge at the proper height. The gap between the 1 and the 3 is 6.8mm, the gap between the 3 and the 5 is 6.5mm and the gap between the 5 and the i is 16mm. (TIS Location: 51 14 110)
Then just applied each number lining up with the pencil lines above the tape. The angle of the first pic looks like the numbers dont line up with the pencil marks, but they do.
