I use an HS Performance reusable filter on my zx-6r and in the wifes 250-R. They are reusable and the micron rating is 35. So far, I'm pretty happy with them. They aren't cheap but if they do the job better than the OEM filters and last for the life of the bike then I don't mind spending more out of the gate. Will pay for itself in time.
http://www.hsperformanceparts.com/
