K&N filter

Does anyone here use a k&n air filter. I have always heard they are the best. I have heard they can add up to 15hp and greater fuel economy. Right now I just have a wix filter inside a duel snorkel air cleaner on my 318. Are the k&n filters worth the $40 or so dollars. I know they last a very long time. Who here has one and what are your thoughts? Thanks