I am not the brightest light in the hall but I do know this.... all internal combustion engines are basically air pumps. If you restrict the intake or the exhaust, then you deminish efficiency of the machine. Race engines can race because they can BREATHE . Any improvement in this capability results in a power gain. All I'm trying to do is free up a horsepower or two. And, if the fuel mileage increases, I won't complain!!