Any recommendations on a good aftermarket air filter? I've been told to get a K&N for the best performance, but I can't find them online, anyone know if the 650 ninja filter would fit?

I,ve been told by K&N that they don,t have one yet- just installed a BMC today- fits fine- seems well made- Italian and similar to K&N in construction.

I've got a DNA filter. Looks about the same as a K&N. It seems quality built.

It is the same application as Ninja 650R and ER6... I got a Piper X foam filter made in UK.

I looked into opening my Air Filter box for more air but was somewhat stymied by the procedure to get to the Air box. Anyone got a step by step procedure for getting to the air box? It really seems very hard to get to and that's a bumer!

You just need to remove windscreen, fairing halves and gas tank to access the airbox. The fuel line clip has to be spread out and moved back to pull out the coupler... Check out page 3-105 and 2-14 in the service manual:
http://www.filesend.net/download.php?f=98497f55dd4f008cbd1668d621e9a5a6
I'm looking into replacing the two airbox inlets for larger ones without enlaging the airbox holes which are of a rounded rectangular shape large enough to accept a larger coolant hose grooved to fit securely. Pics coming soon...

For a step by step i used the information i found elsewher on this site for sub throttle plate removal at http://fortycaliber.org/. only difference is removing windshield and fairing halfs. Be warned though- if you do all mods- bike gets very loud but i find performance gains and response worth the trade.