K&N part # KN-564 Will cost you $12 from some new place called Amazon.com. It's the same as the Buell 1125, because it's the same engine (with mods of course). Use whatever brand synthetic oil you like that is specific to V-Twin motorcycles.

The OE air filter is a cleanable type like K&N, so just clean it. I'm always surprised how quickly it gets dirty. Do NOT spray oil on it.