I put the spacer on my 2002, noticable low end accelaration. The spacer makes a bit of a weez noise when you let off the gas, but i've accutaly had people ask if it was supercharged. Gas milage may have changed by 1/2 gallon more or less. But if you really think about it a 2inch space between the butterfly and body does give more volume of air in the chamber.