I had a new Blown alky engine combo last year. Flowed fuel system. Started to lean it out later in the season and never saw any cad off the NGK plugs. My tuner, said lets try Champ N57DRs he was used to tuning with them and was sure we should have started to see some cad off at least a few Cylinders. Next time out Put in the champs and we had cad burning on several holes. So from the very little experience I have on my engine the Champions were showing cad burn sooner than NGKs.. Going to do some more experimenting this season.... The Champions are silver and the NGKs are gold.
I have always used NGK and just think they are a better looking better quality spark plug...
Has anyone else had this experience?