Just get an adjustable fuel pressure regulator. On your d15 you can run the Zex kit with a completely stock fuel system, however and adjustable FPR isn't a bad idea to up fuel pressure a tad. Just make sure you run one step colder NGK copper plugs, gap them at .030" for nitrous use, and retard ignition timing according to the zex chart.
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2015 Ford Mustang GT Fastback - Ingot Silver - 6M - Performance Package - Gibson Catback, JLT CAI, FR 47lb injectors, BAMA E85 tune, Eibach Sportline, BMR wheel hop kit, UPR oil separator, Steeda shifter bushing/bracket
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