Agreed...if it's not detonation, either spun bearing causing rod knock or the piston to hit the head, or could be piston slap caused by out of round/spec cylinder bore or piston. Gonna be some $ to fix.
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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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