I would think of how much added strain driving the blower makes on the motor, compressing air driven off the crankshaft takes HP and adds strain on every part of the motor, before making the final decesion. As far as turbos I've been told that( by racers who use them) they do add additional concerns off the back side of the motor so I guess there are no free lunches. Adding boost into a motor definetily makes more power easier per C.I. than N/A motor do.