My understanding is that ball-bearing centers have very little to do with full-boost rpm (a ball-bearing center isn't going to make a turbo push 20 psi at 3700 rpm instead of 4000 rpm) but are all about transient response- the time from 0 boost to full boost when you're in the meat of the turbo's effective range. So a ball-bearing turbo won't drop your full-boost rpm from 4000, but if you are cruising at 4500 and go WOT the ball-bearing turbo will spin up to full boost almost instantly. This sound accurate?