In the domestic performance car world Bosch is regarded as one of the worst brand spark plugs you can buy. Most don't know a reason other than it being general knowledge not to use them. I tried to find the test or article that I'm recalling this info from but to my knowledge Bosch plugs don't transfer the spark at the speed of other brands resulting in the equivalent of a timing delay. I remember it was 1-1.5 degrees equivalent.
A previous car I owned, in my avatar, was very sensitive to spark plugs. I had to become a plug expert when modding because the car had no knock sensors and you wouldn't hear pinging over the supercharger. SVT couldn't even get it right and made multiple changes resulting in 3 different OEM plugs in 2003.
I found this on MBworld.com.
As a professional MB mechanic for over 30 years my preference has always been an NGK. They have always provided a superior spark plug which has never failed me. I can't tell you which number to use, but your parts store should have an NGK catalog to look up the proper plug. Don't waste your money on platinum, because your car does not require it.
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300e 24v spark plugs? - MBWorld.org Forums