I have a similar problem, but i am running bone stock (i plan on upgrades soon) but my car sits a full inch low on the right rear. i work for a bmw dealership and was able to get my car on a lift in the shop. one of my tech friends looked at it can can't see anything wrong, but said that the rear shock going bad. I wonder though.....if the shock mount is bad or broken can you see it enough to know? 1 inch seems like alot to me!
2001 330i sport 5 spd, Alcantara M-
steering wheel, 20% Window Tint, Hotchkis Sport Springs, Koni-str.t Struts 18in ZHP M-wheels.