In my opinion after 60 yrs.in the trade K&N air filters are a total waste of time and money, they need cleaning and re-oiling (with “special” K&N oil regularly,they are not particularly cheap and are nowhere near as efficient as the standard filter.I bought a standard filter for my K9 Wee some years ago, changed it and cleaned the original with biological washing powder, then a rinse in warm water and let it dry.It came out as good as new and was reused a couple of times,and it is in my L2 now with a cleaned filter waiting for the next time it is due.I did the same with my diesel car air filter in 2014 when I bought it.Other opinions will be available shortly no doubt.