My '03 still has the OEM plugs at 42,000 miles. Bike still cranks and runs well and still gets the same gas mileage. When I get around to replacing the plugs I'll go back with NGK. :wink:Toyo said:Funny you should ask. I just pulled out one of my Iridium plugs yesterday to look at how it is burning. They have a little over 40k miles on them. They were still in perfect shape and still in the same gap setting. If I would have put in regular plugs I would be replacing them every 15k miles. For me thats 4 sets almost. So they have paid for themselves already in my opinion.
Be ready to change your heads when you change the plugs at 100,000 miles. They might be welded in place.Toyo said:They will go till 100K more than likely.