I have been using Beru 4 electrode plugs in my 103 euro engine and they deliver a brisk performance .The original recommended plugs are good but with them #2 always fouls up ,maybe a little worn seal or guide .
The Beru's simply burn through maybe due to the 4 electrodes, resistance is 2.5K ,chrome plated and euro specs.,Made in France.
mak
300se 103
300sel 3.5 109