High performance ignitions

i've heard from someone that adding an adjustable ignition to your car can help out it's speed pretty good. the one's i've looked at are at www.msdignition.com does anyone know anything about it? good deal or not? i'm planning on adding a turbo in a few months too. can't wait for that one. 2002 cav ls 2.2 ecotech 5 spd is what i've got. and what would that ignition do to gas mileage? i've heard it would improve it...