Designed for use in engines with higher-than-stock cylinder combustion pressures and sustained high rpm use. The Ford Racing modular 3-valve zero degree spark plugs are one heat range colder than the OEM Ford Mustang GT, and two heat ranges colder that the stock 5.4L truck engines.
Note: Engines with late (08-10) style 12MM spark plugs can be identified by coil engineering number 8L3E printed on the coils. Engines with early (05-08) style 16mm "High Thread" design spark plugs can be identified by coil engineering number 3L3E.
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