The 3 vehicles i used to run K&N filters on, all got better gas mileage. Factory airboxes are made with a few major things in mind, cost, assembly time and NVH. I don't see doing maintenance as "more trouble than it's worth". I change my transmission fluid every year, i would never figure it is "more trouble than it's worth". On the other hand, a friend at work who put a K&N on his truck claimed he got worse mileage, he is a lead foot though.