Since you have to remove the upper plenum to change the plugs, longevity is the premium here. I would go with either the AC-Delco platonum or iridium. Platinum and Iridium are denser metals than iron, and as Blazes stated earlier, hold their gap longer, which is their advantage. I have never had any luck with Bosch plugs or oxygen sensors. The gimmicky plugs with multiple ground electrodes are just that, gimmicks. Electricity will always seek the path of least resistance, so no matter how many ground electrodes there are, it will only jump one gap. Do you remember Splitfire plugs? Same concept, and they didn't last because there was no real-world advantage.