You would have to go to a speed shop to get them or you can call NGK or whichever brand plugs you want and ask for them. Basically, just match up the part numbers and there you go. I don't know of any other way of looking at them or testing them to be sure. If you order them tho, the company will send you the right one. Sometimes the supercharger or turbocharger you buy will recommend plugs. Or even some aftermarket heads will recommend plugs. And those plugs will probably be a step colder.
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