On my C4S the radio would stay on for about 2-3 seconds after I turned off the car. This was nice because I would typically turn off the car and then collect my things in the car. Is there a way to configure the PCM to stay on playing the radio for 2-3 seconds like on the 996s?

 

Haven't seen that option. Keep the key in for 3 seconds longer.

 

The radio will stay on after engine shutdown so long as you keep the key in the ignition. Gather your stuff and then remove the key.