I agree with Motormike a K&N air filter turn your bikes engine into a vacuum cleaner, I know our streets need to be cleaned but thats not the way to do it.
For better breathing:
I usually mod my OEM air filter, by pulling off the metal fire screen, it is a flame buster screen that they put on every OEM air filter.
I take that off, usually I get better breathing out of the bike.
Cleaning a OEM Air Filter:
I can, and do, clean the OEM air filter, they are usually a very high quality papery cottony material, that is almost like a hard cotton, when the OEM air Filter gets dirty,
I buy a second air OEM Filter to replace it while I clean the dirty air filter, and have it on the shelf and ready for next maintenance.
I then drop the dirty filter in a bucket of water with some dish washing liquid in it, swish it around a little bit and then let it sit in the water solution for about an hour, go back a swish the water around some more let it sit another hour, then swish it some more back and fourth several more times then take it out and knock the majority of the water out of the filter.
then let it dry on your bench for a few days.
I have also used a compressor to blow the water out of one i need to use by the next day, just hole the compressor nozzle far enough away not to damage the filter but to blow the water out.
Between the two filters they should last you a long time.
I can clean a good quality OEM air Filter at least 4 times before I have to replace it.