Having read this entire thread (sad I know) I'm convinced that without the option you get an actuator inside the car that is only activated in sport mode.
If you do add the Sport and Sound pack as an option you also get red calipers and a different exhaust with an additional speaker built into it.
My question is, has anyone got experience of both of these, i.e. With and without, and can they comment on whether it's worth adding on as an option? I drove one without as a demo for the weekend and found that in Sport mode the sound was great - is it any better as the driver of the car with the option box ticked, or is the benefit only for the people you drive past who experience a better sound from the exhaust!