Here is the real deal guys. Skip white and Viper X are totally correct. I called Dodge and talked to one of their tech guys who told me the viper ignition is designed to run on copper core extended tip plugs only. He said that platnium plugs have a different resistance than copper, therefor you do not get a high enough voltage spark. He says the car will run smoother at low end but you loose high rpm performance which is what I found to be true with the Denso plugs and the Champion double platniums. He also said that by not running an extended tip plug you stand the chance of burning up the motor. As Skip White said before, and I agree, we run $1.50 copper plugs in our race cars making over 800 hp. The problem is that champion does not make a colder plug for the RC12ECC, 438. You can make the plug run colder by gapping it down. I tried .032 and it runs now like a bear and pulls all the way to redline without any flat spots.
