Several who have the 4.4 in their 5 series Bimmers tell me while you might see numbers go up on the dyno, and up just marginally, a K&N filter doesn't equate to a boost in performance. The X has a damn fine stock intake system, IMHO. On the other hand, a K&N is reusable, and about $35 at your local auto parts store, but as Chris pointed out, the oiling of the filter is kinda suspect. Somewhere on the MB forum I once lurked on was a post about some maroon putting olive oil on the K&N on his 500 SEC. The result was a car-b-q as you might imagine.

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JV

What gets us into trouble is not what we don't know...it's what we know for sure that just ain't so