I havent driven it with the K&N Filter and the XH snorkel yet, but from what i have heard from others it is very good. I will tell you later on. The old snorkel is just held in by clips, just push them out and the snorkel comes off, and then get the new snorkel n push it in. no screws needed. and that massive round thing is a noise inhibitor.
But when i put it on, i could feel it suck very hard through the mouth of the snorkel, so its all good.