Ryan, check the archives...this was covered earlier/but yes the theory is the air flow capacity is increased without the foam thus increasing power or mpg depending on how you drive. I don't see where it would make a lot of differance...but I do know that it is louder and that you can "hear" the air flow. If you are very light on the gas, you can here a "Swooshing" noise every time you give it gas while in gear! Check it out, Bill