I recently put a BMC air filter in my 650 mainly because I got sick of replacing the standard air filter due to all the sand that collects in the filter and the the oil that splash onto the bottom of the standard paper filter. Now you can imagine what happens when paper, oil and sand mix :-)
After I fitted the BMC filter I immediately felt the difference in my bike. (okay it's maybe a bit psychological ;-) ) However my bike certainly feels better when accelerating hard and idling sounds smooth.
The BMC filter is very expensive but worth it if you ride your bike hard and do a lot of off road.
Ps. Oil gets into the airbox if the bike is on its side ;-) Or when over filled.
Corné
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