The only thing I was ever told about iriduim plugs, (i dont know if this is true, dont want to find out by trying either), is if you are running lean, the little wire on the iriduim plug will burn off before you burn a hole in your piston. Not sure how much truth there is to that, but thats one thing I was told. I ran them for a little while, but they cost too much for no benefits that I could ever find. I run br8es now with no troubles.