Chill--I didn't say the K&N filter was any level of efficiency. I didn't say it was cheaper either. What I did write about is what I have done for over ten years without any problems in a high dust environment. I am all for the science of studies. They at least make for testy forum discussion. How many times will I see a study concluding caffeine is good for me and the next study not. Studies are like asking a CPA what the number is and he says what do you want it to be? Perhaps that study means other filters are more efficient than they need to be-just overkill. I prefer practical, applicable experience on this one--no offense intended.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas