Since I've ran everything from the factory iridiums to the AR 103's and although the TR6IX seemed to idle better and got me a little better gas milage, I don't know that there was really enough difference to make any real judgements. All of the plugs looked the same when removed and none had any negative effects including a change in knock. I'm a little suspicious of the AR 103's, since being a racing plug, supposed to not last as long and is a colder plug than the AL 103.
There are things that are very difficult to judge w/o diagnostic or lab equipment. Oil, plugs, air and oil fliter...etc. So many variables. Where you live and how you drive may throw results all over the place.
If there is some sort of exacting standard, then I'm game.
