I recently just purchased a 2002 Dodge Ram 1500. I love the truck, but it's a quad cab (6-seater) with a 5.9l engine. The only thing I haul around is my bass gear, but my fuel economy is around 11/15. I did some research, and things like aftermarket air intakes, air filters and exhaust are supposed to increase fuel economy. The question, what's the margin of increase, with either just one of these after market parts, or a combination of them? Is there a noticeable difference in fuel economy, when these kind of things are changed in a car?