I dug a little deeper and found a forum from 2002 where they were debating the champion/NGK issue. It appears that the NGK BUHX plug is a booster gap type plug and it takes more voltage to fire properly and the Force ignition system doesn't always supply the voltage needed. Champion plugs don't demand the higher voltage. An NGK alternative is the BUHW which isn't a booster gap plug and works well with lower voltage. So I guess it's not really a hot issue but rather a voltage issue.