The secondaries are ECU controlled. If you switch to the ITR ECU, they won't open. Stick with your GSR ECU unless you remove the secondaries, or go with a single stage manifold.
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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