I just took my X5 in to an independent shop to have some work done and the owner HIGHLY recommended that I remove the K&N filter and put the stock filter back in. He said the 4% increase in air flow was not worth the $450 price to replace the air flow sensor once the oil from the filter faulted it out.

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2001 X5 3.0i (PP/WP/AP) Traded at 213K miles
RARE White on Black - Why does everyone get Tan??
First E53 with 215s on XOutpost!!