I inquired them some week ago, and in the reply they added:
        
 
         
         
         
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            | At the moment we are working on our own exhaust system (like to one for the normal XT-660). If it is as good as the one for the normal XT-660, then it will be the state of the art system. The exhaust is nearly ready know, we go to the Dyno in the next days.
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         Hope it's good.