I heard that K&N is best when it's use for a while not new. Because dirt that trap in the oil help filter more dirt. Usually I wash it once a year on my wife SUV. My car I wash it 2-3 times a year. I use 409 (degreser cleaning water base) soak it for 2-3 hours and use HOT water to rinse it out. Let it dry over night, then reoil it.
If it faster? I think I feel it, PRM going up a lot faster but I doubt it make more HP (maybe 0.5 hp WOW)