I can't say that it isn't running well. It definitely seems to be for 1500 away from 100k. It just seems to have an unpleasant idle. I will be around a bunch of other XFi's this weekend so I can pay attention to theirs to see how they sound. When I say clunk, its not a loud obnoxious diesel clunk, but almost as if it were a softer one. Reading other posts, it seems our engines have somewhat noise valves? I will follow up on what I hear this weekend. =P