i have had 3 K&N filters on previous cars, and always bought the kit, cleaner and oil. I am sure you can clean it another way, but for $10, I am not sure it is worth potentially ruining the filter.
I do remember this, do not try to dry the filter using compressed air. you can rip that cottom gauze up pretty quick. I drop the orig filter in while the K&N dries
I did not notice any increase in mpg, and the power increase is barely noticed. it seems to run a little stronger on sudden acceleration, but that could be due to the fact my motor is broken in now. I put the K&N filter in right after I bought it. I am going to use syn-blend on my next oil change. I change my own oil to save some $. I can do it for 1/2 the dealer price. I am hoping for a slight increase in mpg. I get 25/35 most of the time, but it drops off in winter. the 10% ethanol blend causes mpg to go down more in cold weather as opposed to warm weather.