first off, make sure you buy the Supercharger new...all the problems I've heard about have been from used superchargers. MSD gave me more complete combustion and a smoother idle. The gas milage I have experienced with the JRSC hasn't been too bad at all. Of course if you have the pedal to the metal all the time the gas is going to be gobbled up right before your eyes. Just have to drive it like the JRSC's not even there...if you have to speed to pass someone or somethin...go for it, you can.