I just got done with the timing chain tensioner replacement/update on my '93 325is.
Wayne's project illustrated here:
http://www.pelicanparts.com/bmw/techarticles/101-Projects-16-Tensioner-Upgrade/101-Projects-16-Tensioner-Upgrade.htm
It took about five minutes. I upgraded to part number BW-11-31-1-405-081.
Just thought I'd point out that for those of us whose worlds cross over to SAE sizes, a 1 1/4-inch socket is 31.75mm and works perfectly for this task. One of my buddies happened to have a jumbo impact set from Harbor Freight, and it kept me from having to find and pay for a 32mm socket.
Also, don't forget you also need a 26x31mm aluminum sealing washer. They don't come with the tensioner.
P/N 07-11-9-963-418-M131
$0.25 on this site. I paid $0.68 at the dealer. Duh.
I haven't driven the car much, but firing it up and revving it in the driveway, it seems much quieter. I just had my smog done today, and listening to the engine at 2800 rpm with the hood open was terrifying. 175k, original cat, and passed, BTW!