copper than platinum. If you have them gapped correctly, they should last you between oil changes. If you run insanes amount of boost and horsepower, they last one or two runs down the 1/4. The Supra guys change them a lot at the track. The latest thing is using Iridium plugs by NGK . But these will only work if you had your spark plug boss removed from your heads. Iridium last about 3 times longer than copper and cost about 3 times as much. They require less voltage to fire than copper which makes it ideal for boost > 2 bar.