I wish I had better data but I don't.I live on a dirt road (1/2 mile) and have put on well over 10k miles and probably 3 years have passed. I pulled my tank the other day and was pretty amazed how clean the filter was and what I could see of the filtered side looked looked like it had been well protected.
Anyway, pulled tank to rebuild petcock but now don't trust the damn thing because of everyone's experiences-ah...the dilemma.
I would not mess with them, unless you are into competitive racing. OEM's filters air cleaner than K&N. . I had an K&N and ruined it because I blew compressed air thru it. You cann't just wash/reoil and reinstall you have to wait for it to air dry. I could ride 400 miles waiting for the filter to dry. JMO~TJ