After lifted up the car, we shook the exhaust system and found out the sound was from the muffler itself. Everything else from the exhaust system is still in good condition. Thus I headed to the exhaust shop and had the exhaust system checked. The boss said that he needed to cut the muffler then only able to inspect the internal whether the muffler can be reused or not. What does the reuse means here is he can recondition the muffler by inserting the fiber back into it if the muffler is just out of fiber.