PASM is the porsche active suspension. The damper and spring rates , as well as anti roll bar rates are different to the standard car. The car sits about 10mm lower than standard all round and when driven in either "normal" or "sport" mode the dampers react and adjust dependant on speed and accelerometers. In sport mode the dampers take a more agressive damping pattern that most consider too harsh for normal roads . In normal mode the damper rate is actually slightly less than standard S spring and damper rates , as a result is ideal for those cars fitted with 19" wheels.
Sport chrono adjusts the throttle response, the action of the rev cut out also becomes more sudden and will initiate sport mode in PASM. PASM can be switched back to normal mode with sport chrono active by pressing the separate PASM button on the dash. To be honest I wouldn't hanker for a car with either of these options as the standard S suspension is well set up and sport chrono offers no gains in performance or acceleration.Bilstein make a very good aftermarket sports suspension that is considerably cheaper to replace than refitting worn OEM shocks and springs , especially if you have PASM where its 300 pounds per damper.
Sports chrono Plus gives you a few comfort functions on the PCM such as delay time and fade on the interior lights and the ability to turn on and off daytime running lights. The PCM also acts as a graphical display and logger for lap times recorded from the sport chrono stopwatch.
for interest I have a car equipped with PASM and sports chrono (plus) with 19" wheels
