SN 93 question

Hey I am new to board and was hoping that someone could help me out. I was wondering if anyone knew what the step up ratio was in SN 93. Also I purchased the one I have now on the stangnet and was trying to figure out if it had the VR4 upgrade. It has a 4" inlet and a 3" outlet. So far I have been able to see about 11 psi at the manifold. I was unsure of what the unit was good for. I am going to machine myself a couple of diffrent size blower pulleys to play with, that is why I am wanting to find out the step up of the unit. If anyone know this it would be helpful.

4.44 Step Up
If it has a 4" inlet then it is a VR4
If you can take pictures of the unit and the impeller I can tell you which model of Impeller. Billet or Cast

Thanks alot, I will try and get a few pics over the weekend and post them.