A simplified example
of a turbo's operation is to compare it to an air pump. The turbo is
designed to reach peak boost pressure quickly, while creating minimal
exhaust backpressure in order to drive the turbine wheel. Performance
turbos differ from stock in a number of ways: most have larger
housings(which increase air-flow,) larger wastegates(that prevent
premature "blow-open",) and some "ball bearing turbos" replace the
bushing with ball bearings providing quicker "spool-up".