Ok there are 2 sets of runners in the GSR manifold: long and skinny, short and fat. During normal driving, the long/skinny runners are used to create midrange torque...the butterfly valve is closed over the short/fat runners. Once you hit 5800 the valve opens, and air is routed to the short/fat runners for max power.
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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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