Me and my cousin just changed my spark splugs today. It wasn't as complicated as we thought it to be. It took about 1.5 hrs or less. Just got our hands pretty dirty. I replaced with the ngk irdium IX...part #6619 from Autozone. My car has 70k miles, but the old ngk spark plugs still looked pretty good and could go for another 30k miles. But, I just wanted to get it done and not have to worry about it later on.