I just noticed something weird that seems to have started happening recently, wondering if anyone else has experienced this. It sounds like there is something in my left muffler or near the exhaust tip that sounds like metal sheets rattling together. When I slam my trunk lid I can hear it, or when my subs hit and I'm outside the car it makes this noise. It definitely is only the left one and I didn't hear this before. Any ideas? Straight to Nissan? I tried holding my hand on the exhaust tip/surrounding area while having someone else close the trunk and it didn't prevent the metal rattle sound.