The dealer replaced the exhaust system once. It did not make a sound for two weeks. Then the problem returned. As I was trying to get the truck back to the dealer the engine blew. Head failed on the drivers side. The brackets that hold down the overhead cam failed or something caused them to fail. The dealer was trying to get Ford to replace the engine to no avail. They picked the cheap way out and only replaced the head. They could not determine why the head failed and also found metal in the oil pan. They mentioned this could be from breaking in the engine. That is nonsense. They just changed the oil for me when the exhaust was replaced the first time. Now Ford is telling the dealer that the exhaust noise is a "NORMAL CHARACTERISTIC" for this model. BULLSHIT! If this truck would have made this noise when I test drove it I would have never purchased it. It is very embarrassing noise, especially sitting in traffic next to a Chevy or Dodge. The dealer is still trying to work whith me but I don't see it going anywhere with them. We will see. As far as I'm concerned this is totally unacceptable