I've had my car since it had 8k miles on it. Now its around 76K. I've never changed my spark plugs. Should I look into doing so? The car runs just fine with no indications of any problems (knock on wood). So if it aint broke don't fix it? If I do need to change them what would be an upgrade over the factory plugs (I'm assuming their factory since I don't believe a car with only 8k would have them changed already). Thanks for your help.