First, NGK does not make an Iridium CM-6 plug. DLE is marketing a CM-6 type plug under the Iridium name. That's a full copyright infringement btw. Based on what our gov is currently doing to correct those issues any non NGK plug entering the states with an Iridium label may not be coming much longer. NGK does make Iridium plugs, but not a CM-6. Perhaps try something like a CR6HIX, but they sure won't fit our engines.

As for lasting longer than a CM-6, how was that information derived? The DLE plug has not been in existance long enough for that information to be accurate unless a series of plugs has run continuously for better than 200 hours each. If that is the case, what were the engine serial numbers, where were they run, who conducted the tests, and where are the run comparison plots for verification?

Need to get your facts straight and recognize that there are some people out there that have been working with this stuff for years, work with new ignition designs and concepts, work with various plug types, and know products pretty well. That fails to take actual engine running into consideration, which would be a formiddable task to exceed.