RE: NGK CM-6
No flame from me, this is old news. Though I do have several stock DL plugs that have been running for multiple years with no problem whatsoever, this past summer I did start seeing first hand some of what I've read about the stock plugs. It seems if the stock plug works for more than a few tanks it works and lasts no different than a CM-6. In my experience, if they are bad they go out very quick. I do use and sell CM-6 plugs as replacements for the originals. Several threads on the price and availability of the NGK CM-6 plugs have come and gone over the last couple of years.