So with the original question in mind. If he did want a longer lasting plug, but still wanted it to run very good. What heat range of iridium would u guys recommend. For both Zetec and SVT? I would think you would want a step or two colder plug than stock(in both the zetec and SVT) correct?kylebal said:ok i have iridium spark plugs on my svt are these good to run with 10 psi??