copper cores. its the best plug still to this day for the boost application. they are super cheap too. i order mine from cfm. They just have to be replaced more often. but hell for $2-$3 per plug you can change them 3-4 times as the cost for something like iridiums.
Too Fast For Me... TONS OF WHP... GOBBS OF WTQ......
Go ahead put your car where your mouth is....
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