Maybe something is loose? I haven't had this problem. Hope you find it. How is the drone with yours? Do you have the baffles removed?
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2014 GT/CS Deep Impact Blue M6
JLT CAI, Bama 93R Tune, Boss 302 Quad Exhaust (baffle removed), Roush Axel Backs, MMD 551C Matte Black 20x8.5 in front/20x10 in back.