I'm going to take my car in to get check don't worry. But I'm a little stumped as to what the problem might be. I am getting this strange knocking noise from my muffler and it sounds like someone just does a random bang on it. It's not really loud but it's loud enough that I can hear it in the car and while getting out. It mostly happens when I'm waiting for the car to warm up, cutting it off or at a idle at a light. Does anyone have any simaliar experiences?