Recently purchased 91 420SEL and the PO was using Bosch Platinum resistor plugs. I want to replace these with NGX copper, but here's the question. The end of the bosch plug where the wire goes has a small threaded stub. The NGX plug looks like a normal plug.( Slightly larger rounded tip. The NGX will not fit in the current wires. Do I need new wires or is there an adapter.
Thanks

Take a pair of pliers and screw the tips off the NGKs.

Of course, the plugs you should use are those recommended by Mercedes. There are no "improvements" out there.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

My bad, they are NGK, Still looking to find Bosch wd8co
Thanks

Try NGK bp5es from Oreilleys auto parts. They are non-resistor and are less than two dollars each. I have them in my 420SEL and am very happy with them.

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual

Thanks,
I picked them up today at NAPA for $1.99 ea. and installed them already. Car sounds good. Also the stock # for NGK BP5ES is 7832.