It would be nice to have the option of a horn sound when set or a option not to have it.
Many vehicles offer a chirp or brief horn tap when the car is locked. Some owners love the feedback to confirm the car is truly locked, while others hate the additional noise. Having an option for this feature would be ideal. Most luxury cars also dispense with the horn and have a far nicer chirp that is distinctive, but not annoying like horn based systems.
(Notes added by Moderator)