[EAGLE5]

Cylinder temperature and pressure over time break rods. It's not about psi or some vague concept of boost. Running a supercharger at a higher speed will leach more power, but it's not going to put massive strain on the engine, nothing like the strain of more cylinder pressure or temperature. More efficiency is a good thing, of course, and for the same WHP would likely mean lower temp, pressure, and fuel use. If you're running a stock engine, making a lot of power down low is a bad, bad idea. Where the stock breaking point is will vary by engine and tune.