If you ever get a chance to look inside a set of Magnecores you will never run them again. I had a set of them on my CS '99 Sport years ago, I started getting some missing. I started by pulling the spark wires and one of them (Number 2 wire) had come apart at the spark plug. The inside of the insulator is hallow, with a very fine, think two strands of hair, wire coiled inside. The only thing conducting is this very fine coiled wire, the NGK blue's have a much larger gauge wire as well as better insulation. The down-side to the NGK's is that they do not last more than 20,000 miles when used in extreme conditions (i.e. hot climates, racetracks etc.).