Well, although Bosch says it's OK to run their resisted plugs as replacements (and MBs use a Bosch ignition system), I agree that resisted plugs are probably not "ideal" for the reasons already stated. I delved into this a bit a few years ago, and according to MB tech info from the era (I didn't have access to WIS back then) the extra resistance from the newer Bosch plugs certainly won't hurt anything, still well within the allowable range -- contrary to what I've heard some mention on another board. (Of course, there could be some more recent info that I'm not aware of, and I'm certainly open for correction here.)

I've seen cars with aftermarket wires using 5k plug-end caps (should be 1k on most, the 5k caps are supposed to reduce interferance a bit more) *and* resisted plugs, they run OK, and in some cases have for several years. It's certainly possible though that the resisted plugs may not last as long, and FWIW I run non-resisted plugs.


EDIT -- Just a thought here, but I've personally not seen proof that a resisted plug will diminish the spark so much that it would cause incomplete combustion, hamper performance, economy, etc. Becasue it's resisted doesn't necessarily mean that there isn't enough juice across the plug for complete combustion. My $0.02 anyhow...