Hi Gerald
As far as I know, he has no bigger wheels and NGVs. That was also the reason he sold me the 84mm NGV and wheel. But now I know because of different measurements and calculations it is too small. I've already some ideas for creating...

I would like to talk with you once more about your design of the diffusor. I have calculated the turbine on the basis of Thomas Kamps and there I get an angle of only 18.5° for the angle alpaha
Thomas Kamps also wrote in his book about “backward curved blades compressor“ and then to use an angle of 21° for angle alpha. For “vertical blades compressors” he recommends an angele of 18°. So the compressor I use is the same as you took.
Which amazes me is that you have even steeper angle of 22°? Or is it the angle bisector who counts?
Why do I ask? It's because I'm still fighting with rotating stall or surging when I make the compressor more effective by closing some holes and move the inlet closer to the compressor

Attached you find my drawing of your diffusor with additional angle information.

happy to hear from you
regards Lukacs