Just to clarify- Borg Warner (who make the turbos) do not recognise a K03's' there's no such thing. The differance between a forum 'K03s' and a normal 'K03' lies in the actuator strength- which dictates the boost pressure the turbo can provide.
Pete- I'm sure that's crap, they're all solid bearing, never seen one with roller bearings, although I guess you could upgrade them...