From every thing I have read about the iridum plugs, they are harder then platium. They deal with heat bettr, they help to get better gas milage. They help over all performance. That is why I bought them. I didn't want to spend $9.00 a plug, but if it improves the gas milage and the way it runs, then I will try them. I just bought a FRAM oil fliter that does'nt need to be changed for 10,000 miles. I paid twice as much for it and the advanced technology that came with it.