You have a rev limiter built into the DME.

As JFP said, the DME (engine computer) will limit the rev's by selectively cutting the ignition and fuel. No valve float will occur at this RPM.

And that is why the rev limiter only works on upshifts. On downshifts, the engine can be mechanically forced to turn at higher than redline RPM's and cutting fuel/spark will have no effect. These are called over-rev's and are logged in the DME. Over-rev's can be read out by a Durametric tool.

This is untrue. He would have said "heftig". Mr. Ferrari may have said gusto ,but not Dr.Ing. Ferdinand.
The good Dr. would also limit his recommendation of heftig behavior to those cars that are in perfect mechanical condition with a perfect Porsche maintenance history.
Flogging a worn out Porsche with incomplete maintenance is not a magic cure.Ask Mr.Stone what happens if you do it! Expensive.

There is an ignition rev limiter, it cuts the fuel when you get up near the redline.

Edit: I didn't see the other replies :)