well....gas milage will pretty much remain the same unless you open up the throttle alot( driving w/ high rpm's) which will eat up alot of gas.....i shift at about 4k rpm( dont always shift there, only while driving to save gas...asctually its about 3-4 k rpm)...gas milage is still good.....dont have much info on tha swap though...i think thats where v tec kidd chimes in....