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And, should it continue to be used with the orange box or a MSD ignition?



beaten to death but i'll bite. what coil? assuming a performance one then -
1)orange box - recommended
2)MSD - no

the purpose of the resistor is restrict voltage(thereby current) to the ignition system. it reduces the operating temp of both the coil and the ecu. it also increases point life for those that have a points system.