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As a precautionary measure, Zex recommends running colder heat range spark plugs to further resist detonation. On this Hemi, we installed NGK's 4306 plugs, which are one heat range colder than the stock 5306 plugs. As well, we ran a slightly tighter gap: 0.040 inch as opposed to the factory-recommended 0.044 inch. To ensure we have sufficient spark, we also installed a set of Taylor 8.2mm plug wires; misfires or weak coils could result in big problems, so we didn't want to take any chances.