Which type of MB are you doing the injector replacement on? For V8s, you'll need a 12mm (MAC long handle preferably) combination wrench, special tool for adjusting mixture when it's time to adjust lambda. This tool is a long screwdriver (5 or 6mm I believe) made by Hazet, and for those pesky nozzle holder clips, a long needle nose would be helpful. And obviously a 10mm for removing the air filter housing.
P.S.--You'll also want a dwell meter for mixture leaning or richening (lambda adjustment), to monitor injector pulse @ 3,000rpm. And some M-B 'Gleitpaste' for the injection nozzles to make the holders slide on easier always helps!
'67 250SE Cabriolet
'93 300E 2.8
[This message has been edited by Aaron (edited 08-17-1999).]