****** - Verified Buyer
4.5
Great plugs so far (about 500 miles). Previously ran NGK TR6's in my GT500, running about 15PSI boost w/.035 gap. So far these seem to idle/run even smoother (but don't new plugs always run smoother, will have to update review after $10-12K miles or so... noting that I replace my plugs about once a year anyways, so I always go with the inexpensive standard plugs and not the pricey iridium).