I have the Borla atak. Sometimes when I get on it real hard and heat up the exhaust I also hear rattling as if it's touching my floor on the passenger side. I've taken it to exhaust shops had them weld in new hangers and it helped but I still hear it from time to time. I've got under the car at least 5 times to see where my clearance issues were and there's at least 1 to 2 inches of clearance at the tightest spots so I have no clue where it's touching if its even the exhaust making the noise.
But it's only when it gets driven hard. I even had Borla replace my exhaust under warranty because I thought the inside of the exhaust came loose and even with a new exhaust it makes the same sound.
2012 Grabber blue, Auto, Eibach pro street S coilovers, MM caster/camber plates, Borla ATAK cat back, off road X pipe, A.E.M CAI, SCT-x4 Mike Roush tune,SR LCA's, BMR Relocation brackets, J&M Pan hard bar, UPR Catch can, SVE 15x10's, Mickey T's 275-60-15.