Hey man,
We looked at several different centrifugal blowers before we started our project. The biggest problem we found with almost all of them are the dimensions. It is kind of funny to think, but a big roots blower is a lot easier to fit in our engine bays than any of the centrifugals. Even the tiny Rotrex we are using has to be kind of shoehorned in. We actually have a Powerdyne unit that measures a little smaller than the smallest Procharger and Vortech units, and the only places it would fit had nowhere that you could begin to mount a bracket to.
If you are looking to go that high in boost, and you want a centrifugal blower, I could probably hook you up with a Rotrex unit that is the size up from the one we are using. It doesn't even have to tap engine oil for lubrication anymore.