Sorry... can you please complete a thought and post it.
Liek intake runner, lower end???? <~~ I don't get that.
There are no runners on a supercharger. Runners are part of a lower intake manifold.
What are the casing differences? You tell me, I haven't seen them side by side where I could compare besides on sites. Therefore unsure what the differences are.
Here is what I know. If the rotors were the only difference, then everyone would be swapping rotors only.