TookyCat said:If you are on a budget like me you may want to consider the opportunity cost of the ball bearing center section, i.e. could you take the $600-$800 and spend it elsewhere and see more benefit? You could get a set of good flowing heads for that $ and flowing more air would probably help spoolup more than different bearings would. Just an alternative point of view,
PS: I saw Typhools BB turbo and it does spin for minutes after the engine is shut off!!