True, there is no power lag using superchargers, but there is a price to pay. First, they drink gas while turbos can help gas mileage, as long as you don't have a heavy foot. Second, superchargers suck up alot of power to run them.
The Shelby Mustang engine produces 800hp, but 150hp is lost to running the chargers' belt drive, leaving it with "only" 650. The car must still have cooling systems as if it produced the whole 800hp, which add alot of weight to the car. Don't get me wrong, though, if I could afford the Shelby and the gas it burns, it would be in my driveway, yesiree !!!