If you've ever looked at a classic American muscle car, such as a Dodge Charger or Plymouth Road Runnerand thought, “this ...

tuning your HEMI engine begins with one of two additional steps: Either send your stock PCM to a shop or tuner manufacturer to be unlocked, or swap it out for a ready-to-go unlocked unit.

The first stop for any performance modification on a car is typically getting a tune, and HEMI engines are popular enough that owners have several options.

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Dull on the outside and spartan on the inside, this 1966 Plymouth Belvedere is the perfect sleeper thanks to a Hemi swap.