So in the hunt for better gas mileage in my supercharged lifted 04 Tacoma what have the rest of you noticed in decreased gas mileage when you have added one of the above thats above the roof line? My plan is to add a RTT to the back of my DC Taco and try and keep it below the roof line because the truck already gets bad enough mpg's but I want to know how bad a hit I might take if I cant keep it that low?