I don't know if its already common knowledge or whatever but I figured I'd add my story:

I have the cxracing T3/T4 (46trim .50 a/r compressor and .63 a/r stage 3 turbine) and hated the .63 turbine....too laggy for what I want. So first tried the .48 a/r stage 1 one from my originial turbo and got my early spool back but it felt choked up in the higher RPMs.

Onwards to the point, I figured I'd pick up a garrett .48 a/r stage 3 housing and use the churbo stage 3 wheel...and they definitely don't mix. The wheel fits the housing but the inducer fins are slightly longer than the real garrett wheel and it binds up once assembled.

So I'm sure the churbos are all over the place and maybe others are closer to garrett's real specs but definitely not the cxracing one.