I've never seen any objective data to suggest there was any measurable HP gain by using a K&N filter.
I have seen anectdotal evidence over ten years of owning a BMW of people gumming up their MAF sensor by over-oiling.
I have always used, and believe in, only genuine OEM filters for my cars.
YMMV of course. Just my 0.02.
Character does count. For too long we have gotten by in a society that says the only thing right is to get by and the only thing wrong is to get caught. Character is doing what's right when nobody is looking... " --J. C. Watts