I will just jump in, and say its not a ball bearing unit. We have found through extensive testing that to retain the spool N54 owners look for, you have to size turbos on the smaller side, this means elevated shaft speeds. Adding a BB to the mix means you have now added a very real upper RPM limit that did not exist in the JB units. We will never offer stock location, stock type casting BB units for these cars. You are opening yourself up to failures while picking up very little in the way of decreased spool time. We currently do offer BB turbo upgrades for the N54, Stage 3 kit uses twin Genuine Garrett Ball Bearing units...