Most people mistakenly install fancy spark plugs in their vehicle, especially a given brand's "top" option. The fact of the matter is that most vehicles perform best with the OEM recommended spark plugs. This especially holds true for older vehicles, and platinum or iridium spark plugs will do nothing to help vehicles from the mid-90s and older. Too many people waste money on higher end spark plugs. Certain vehicles can benefit from them, but most do not. What are you putting in your vehicles as far as spark plugs are concerned?