you are surposed to use them with ball bearing turbos as they are far more intolerant of dirty oil than plain bearing ones, however you really should try and keep your oil system as particulate free as possible :wink:
Forced Performance make one for both ball bearing, and bush bearing turbochargers. The only concern I had, was what if it got clogged, and I wasnt aware. So I've fitted a pressure gauge between the filter and the turbo.