That is a convenient misconception. However you sir are misinformed, and contributing to the problem.
Also it is quite obvious that this can't be true because the configuration of the cartridge housing is completely different than any of the mitsu turbos. For instance on subies the water inlet/outlet are on the same side of the housing. On Mitsu turbos they are on opposite sides.
The parts BNR use are replica's/knockoffs/interpretations/what-have-you of the MHI compressor wheel and turbine shaft. They have to machine these components and re-balance them, and machine the housings for proper clearance. It's not a MHI wheel, turbine, bearings, etc etc etc.
If that doesn't convince you that you are spreading misinformation(which it certainly should) Here is an email response from Bryan last year when I ordered my BNR 16g.
Sorry to burst your bubble. He does make a good product though. I've put 30k miles on my turbo since I bought it last year and it works fine. No complaints here.
It does make me curious where he orders his parts from if he doesn't order them from MHI. Maybe from Kamak?
When this one fails, I'll be purchasing a Kinigowa.