There's a lad on Audi-sport.net who builds the k03 k04 hybrids with an RS6 compressor wheel and ball bearings.
When I was last at R-Tech I asked Niki about a Loba k03 hybrid I had my eye on at the time, and I got the impression he didn't want to commit to saying "it'll make 350bhp" or words to that effect, because he wasn't familiar with that turbo. Which is fair enough.
He is, however, familiar with the Beach Buggy Turbos hybrids, and tunes them to great results. I know he trusts the quality. So when the time comes, it'll probably be a BBT for me.