OK...I just called NGK's technical support. The rep. basically told me that the OEM NGK plugs, which are more expensive, will typically last 80k-100k miles and are laser platunim with 4 nickel grounds. The cheaper NON-OEM iridium plugs typical life is 40k-50k miles and have 1 ground.

He said that the iridiums will actually give a very slight performance advantage, but at the expense of a much shorter life.

So c4racer, you can buy those plugs from Amazon and save money now, but you will have to replace them twice as often. If you don't change them yourself, I would bet the cost to have them replaced negates any initial savings.

Hope this helps.

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Profeshenal spellar