my understanding is that a supercharger is being run off a pully from the engine and is therefore running all the time, where as a turbo runs off the exhaust gas and therefore has lag. A supercharger may be running all the time but cannot provide as much max total power as a turbo. so basically the turbo has lag but a higher max power and the supercharger runs all the time but doesn't create as much power. that's my understanding...could be wrong.