If it is a Supercharger that runs off the same belt as your accessories like a Procharger, it will make LESS.
If it is a Supercharger that has it's own drive belt it will not matter, to increase or decrease boost you need to change out the crank drive pulley for the blower. Most guys go to the 7" lower pulley on a Vortech to add 2-3lbs of boost. ASP and others sell the pulley as a 1 piece which incoporates a undrive accessory pullies