Well, my NT is a 2010 with 28k miles on the clock. Not too noisy... until 2-1/2 weeks into my son riding it around and to work. Now this (audio file extension not allowed?!) it clatters all the time, no wavering with revs. Seems like rear cylinder cam chain slap. Same as my old KIA when it failed. Gonna pull valve cover, change oil and filter and maybe tensioner. Hope not directly valve related. She deserves better. But you'd think that the engine revving 5k rpms at 70mph would never have that specific problem. Sounds like an engineering flaw.