65mm x 74mm 11 blades vs 75mm x 83mm 10 blades. In the last pic you can see how much more open it is in the center of the scroll on the 75mm. Also measured the compressor wheels. The 76mm and 78mm both have a 102mm exducer. Compressor blades look like the exact same design.

 

Be cool to see a back to back drive pressure test to see the difference.

Does On3 offer larger A/R exh housings for the 78/75? If they don't, since these are a copy,does anyone know what brand would fit?

 

That would be a cool test. If I had time to throw the old one on I would. However I will just log what the new one is and then compare that to the next turbo i get. I know the 65mm would be awful.

I don't even recall ever seeing anything other than a .96 for a 75mm turbine from any brand. The turbine housing does look identical to the 65 though besides the machining in the center. I know there was some 1.32 or maybe 1.5 AR housing for the 68mm turbonetics at one time. I read that comp turbo would make you some a few years back. If you could find one it probably wouldn't be to bad to machine for the larger turbine.