Installed a set a Autolite copper core 3922's today. Changing plugs is a piece of cake when you have the proper tools, which I usually don't.

The tools work so great, I have to post up a link to a set:

http://www.ebay.com/itm/Mercedes-Spark-Plug-Wire-Wrench-and-Socket-Tool-112-113-/370764751584?pt=Motors_Automotive_Tools&hash=item56534d22e0&vxp=mtr
This is the best money spent to date on this car, besides performance mods.