I change my plugs every year, so I use the best plug ever made, the simple, cheap, copper plug. The ONLY positive thing about the different metal plugs are the fact that you can run them for tens of thousands, some even hundreds of thousands, of miles before a change. The metals are harder and do no degrade or corrode as easily as copper. They do not deliver any better performance and could even hinder it slightly. Think about it. . . Do you run copper wire to speakers or do you use iridium or platinum? Which is the better conductor? The same applies to plugs and wires, hell any electrical part of the vehicle.