JohnnyN Didn't really notice. A change of plugs needs to be looked at on the dyno for any noticable gain. Before and after runs. TBH, I don't think that there would be any significant gain. As mentioned before, they are a cooler plug for higher temps.
Matt I read this with interest. I too went out and bought every type of plug that was compatible with the z22se and found the standard GM ones the best.