Did this yesterday and rode out today. Mine was different to the rest of you it would seem, I guess model year 2015 is different,
This is the top of my airbox
https://drive.google.com/open?id=1gWcH1O-33Y6QaxTPS6UPEKDOUTlusPfP3g
This is the bunged up pair valve
https://drive.google.com/open?id=1_tvtzku4JIbw--KSbUmPEz8QoFaHolqejw
This is the end on the underside of the airbox which did go to the Pair valve, I blocked this too
https://drive.google.com/open?id=1-CDMvjqFjtZS76zXmDLaCmsR7NgwK7fqxw
And these were the pipes removed
https://drive.google.com/open?id=18nyfTa94S8cHc0mYjCtaE9nrHSJoo0mPhQ
there were two pipes coming out the bottom of the airbox at the rear, a clear one and a black one. The clear leads nowhere so I'm guessing its a form of drainage, the black leads into the gearbox so maybe a breather pipe? If I've only half done the Pair valve removal then someone please tell me!
The bike certainly feels smoother on the throttle at low revs, less jerky. The nice burble in mid range when backing off is there still, not changed. The popping is maybe reduced by a third, it got more frequent the longer into the ride it got. It never really annoyed me as I liked doing it on command which I can still do but it's not as loud a pop now. I'm not sure if the next bit is my mind playing tricks on me, I'm sure there used to be a hissing/pulsing noise which was faint and you could only really hear it when you puled the clutch in while moving or when you were stationary... well this has gone.
I'm using a full akrapovic system (headers, decat and slip on with k&n filter, no PCV...yet)