The tensioner automatically tensions the belt, so loosening the nut on the tensioner will release tension on the belt. Don't remove the nut completely, just loosen it a bit. When you are done, make sure you torque it to the correct spec, then set belt tension as shown in the how-to.
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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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