My cars have ran way cleaner (smoother... you start the car up and it just sounds "cleaner") with iridiums and they take to higher boost better than coppers. I had high boost missfire issues with my 1g , put iridiums in, and it cleared right up. The same plugs have been in that car for over 2 years now, and still runs @40psi without a hiccup.
They're around $35 shipped from rock auto, really not that expensive, and never worrying about plugs is nice.