Sorry, you are wrong.

N62, N63, S65 – Twin cam (two cams for each bank), 4 valves per cylinder, produced from early 2000s to current Cylinder numbering is 1 through 4 on passenger (right) side and 5 through 8 on driver (left) side. numbers 1 and 5 are at the front, 4 and 8 are at the rear.
Ignition firing order is 1-5-4-8-6-3-7-2 (except S65 = 1-5-4-8-7-2-6-3).
Bank-1 is the passenger side (cylinders 1 through 4), bank-2 is the driver side (cylinders 5 through 8).



Also, if your spark-plugs are over 100K it may be just that. BMW suggests you replace them at 60k.
Good luck.


Sources:
- BMW Engine Firing Order and Cylinder Location (Bank-1, Bank-2), 4-cylinder, 6-cylinder, V8, V12 | Bavarian Autosport Blog
- http://www.bimmerfest.com/forums/att...5&d=1300909982