Pedestrian warning system speaker retrofits available for certain Model 3s made after July 5 2019 through September 9 2020 as this period represents the timing of when the wiring harness was included but not the speaker (all Model 3s built since early September 2020 have the speaker already installed) . Model Ys built before August 14 2020 also qualify.
I’m told the cost is $200US and must be done via service visit or mobile, not by the user as the car config must be updated by a tech in order for the car to recognize it.
Refer to Tesla SI-21-90-001 when you make an appointment to have it installed for reference.