you downshift prior to turn in, usually while you are at max braking in a straight line, meaning any extra braking from downshifting without revmatching will lock up the tires or throw you into abs pulsing. Neither of which does ANYTHING to shorten braking distances. Please don't ask how I know. I will say that catching reverse instead of second and doing a reverse burnout at 20 mph does do amazing things for slowing a MGB.