I have the single NW, and hope to upgrade to the dual some day. If money is no object, go with NW dual. You will be amazed what happens the first time you stomp on her. You will hear the SC whine for the first time, and what a sweet song she sings. And, the new power will be more than anything you would have expected. I recommend that you take someone with you for the first ride after install and have them video tape your expression when you go WOT.