to be totally certain, I might dab a bit of silicone gasket sealant on the PAIR valve cover, since that plug will see positive air pressure. Maybe the other part too - wonder where the other end of the hose plugs into the exhaust? To be fastidious and anal, I'd actually remove the hose and plug the exhaust, just so that exhaust gases can't leak up there. A minor thing, but if you're not that picky, you're not really an obsessive tuner
Normally through the cam cover, then a reed valve (one way valve) before entering the exhaust port
Previously.........09R1, 08R1, MV1000R, MV1000S, KTM SDR (POS), MV 750S, Ducati S4, S4R, 748R, 98R1, and about 40 others........