You don't see them on top drag cars because of turbo lag, a specially built turbo could easilly generate the power, but you'd get a lot of lag from the turbo spooling up. Turbos and superchargers provide difference characteristics. It really depends on the characteristic of the car the manufacturer is trying to give it, turbos create a lot of high end power but have turbo lag, superchargers create the power low down but don't have the lag. What's best for any car depends on how you'll use that car and your preferences really. In some applications one is blatantly better than the other. For example, you don't see turbo's on top fuel dragster, bcause they don't provide the needed characteristic, in contrast, you find circuit racers opt for turbo's more than superchargers because they spend most of their time in the upper rev bands which is where a turbo would be most efficient.
My meaning from what i said was simply because blowers produce more power in a wider range of revolutions from the get go. When it comes to power you cant beat a supercharger. Hence... turbo's are no where to be seen. Now turbo's have there place of course just like everything (i know.. i have a machine with twin turbo's AND twin superchargers so they have there applications wihtout question).
