as soon as you upgrade the injectors the stock ECU is going to be very cranky. the resistor packs will only change the injectors impedence (high/low), NOT help the ecu deal with the bigger injectors (more fuel going in for same injector pulse time).
You can either get yourself a piggyback fuel computer or go full aftermarket... depends what other mods you have planned, but I have a general bias against piggybacks and say go aftermarket
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