The blower certainly takes a couple hp..
In the end however it simply is a matter of fact that an engine is an airpump. The power its going to make is simply a factor of how much air and fuel can get stuffed inside. That really doesnt change depending on what method of forced induction is used. ( blower, turbo, N02 )
Turbos do steel hp as well.. There is no free lunch and the huge restriction in exhuast flow will cost something. I dont know enough to tell you what those numbers look like or how they compare to a blower.. Anyone else know ?