Hmm, strange, i tried them in my 260, and got no gain whatsoever. Man was I "perturbed". I know there is no index, however I have never had a problem with "bounce" ignition (I think) Anyway, I still think that the supposed gain does not validate the cost. And yes, Even before you think it, I am Cheap. After all, I'm on a limited budget. I have an AMC to Feed!