The biggest problem with so called Intake & exhaust performance Mods, is that they make one punch the throttle more just to hear the engine growl. This of course leads to a decrease in mileage. I have never liked K&N. However, I do believe that some of the performance Mods do work. But they will never be felt unless you are on a motorcycle, which is more sensitive to small changes. Obviously, no one Mod will add hp but if you invest in over 1000 dollars with several Mods, then you may feel something. Additional hp does not come cheap. If I were to seek more ponies, I would settle for nothing less than a Blower. This is because after making an investment, I want no doubt at all that it made a difference. Nothing offered on the market will add gas mileage