Irridium plugs IMHO are a waste of money. I used the stock Copper Plus plugs in my 280 hp '03 GT and use the stock Copper Plus plugs in my 350 hp '05 SRT-4. Both cars are beasts and run very well. While irridium may last a bit longer I can get 4 sets of stock Copper Plus plugs for the price of a set of irridiums. It's your car so put what you want.
