Originally Posted by
Nexus Flux
Well there you are heading in Ian's direction. By using heel-toe downshifting to brake you are using the engine to do some of the braking. You do this by doing some rev matching but still using the energy of the car moving forward to drive the engine meanwhile the gas pedal is mostly out so the engine wants to idle. The energy is shifted from the rear (in a RWD car) through the drive line (assuming no slipping/properly working clutch, at this time clutch is fully engaged, and the sychros are just chillin') to drive the engine. If done properly and at a correct/safe RPM, this will overdrive the engine but will not result in dangerous over reving (sky high RPM level).
Wheew... That's my ::2Cents::