Just changed the o2 sensor on my 92 525i. I had been dreading it since I was under the impression that you had to lower the exhaust. But I found out that with the proper tools ($10 o2 sensor socket from pep boys) the exhaust does not have to come down. It is a little cramped but really not that bad. It took 15 minute from beginning to end. Also replaced the valve cover gaskets (leaking oil into plugs) and got some Bosch +4 plugs. The girl is running like a wet dream now. I would like to thank everyone one this board for always being so helpful.