I'll have to pull one of the plugs and check. I know that with my 2000 GTP I went copper and changed them on a "regular" basis as I was all into (slowly) modifying that car. This one being stock, I went with AC Delco Iridium plugs I believe (I'd have to pull one to make sure).

Also, just as a general update. We were gone most of the weekend and took the family van, so I still have just about 3/4 full tank of gas to get through before I will be able to fill up with premium.