For it to make increase in performance, the stock filter would have to not let enough air through for the optimum performance from the engine. Obviously the manufacturer wouldn't design it that way, so you won't really see any gains performance wise from just a drop in filter. As for fuel economy, some say they do gain a few extra mpg's, but alot say no.yea i love because you dont need to make any under hood mods. anybody see any increase in hp or torque? i know some cars get small gains from them.