Got one in my GSA WC, been in now for 62,000 miles, just done a service after a 5500 mile trip around Alaska, filter was full to the top of the ridges with dust, air box underneath was spotless. Just washed it out and re oiled and is now ready for Morocco next week, at a guess it will want cleaning again when I get back. I clean it every time I do a oil change so that is now 10 times, works out cheaper than a standard BMW paper filter and I could possibly sell it if I ever get rid of the bike