G.Ballast Resistors - Electronic Distributor 1P5206436 1P2444641 Ballast Resistor, For Electronic Ignition Systems, Using P4120505 Orange Box and Production Coil, or With P4120889 Coil, 1 OHM
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http://www.mopar.com/assets/pdf/performance/catalog/Ignition_&_Electronics.pdf
Mopar recommends 1 ohm. With their coils, maybe anything lower will cause too big of a current draw for the ecu.