Leave it in D4, wait til after 3k or so to spray. I'd also pick up a window switch to turn the nitrous off right before your tranny shifts...just for safety.
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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
Team B.O.B.® - Ballaz on a Budget