Will a drop in K&N or and edge module bring up the mileage. I get 7 to 8 mpg towing my trailer and I sure would like to improve that. I see someone states they have an air box mod. I would appreiciate any info on this. I did have the oil level increase problem happen after the dealer changed the oil last time. Never before did it happen. I got back from a trip and the oil is the same level , no increase yet.