I have been using a K&N filter on my diesel pusher ISB 275 for a year and it works fine. I have a 32 ft and pull a Chevy Silverado 1/2 ton. On our trip from Az to Perry FMCA we traveled 2150 miles a got 11.003 mpg. Its about the same milage as with the stock paper filter. I don't see changing the filter has any positive effect on milage unless the old one was plugged.