Ask anyone who really knows MB's and has been working on them for years. They will say use the cheap Bosch copper plugs. All they way up to the late 90's actualy. The M112 V6 and the M113 V8 are some of the first engines that require plat plugs.

Spend your money on something else, buy the $2 plugs.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200