I called Bosch Customer Service (888-715-3616). They called me back.

I was told that the #09027 are the correct Bosch wires for the 4.5SL. He could not explain why box says for Mercedes V-8 AND also for American & Asian cars only, but thought it was because it is a generic box.

He said we should be using resistor plugs and that WR7DC+ were correct for the car. He said the lower wire resistance should improve things. He did not know what the resistance of the plugs were.

The rep was not too convincing, but I guess car runs fine, so why argue with success?

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5