I created a service request on the Tesla app under the "Software Update" section to see if Tesla would add Boombox to my car. At first they tried to brush me off by saying that my car didn't support the feature, but I let them know that I installed the wiring harness and speaker myself and that the pedestrian warning sounds played on drive and reverse. So they offered to try adding Boombox remotely for the regular installation charge minus the parts cost. I agreed to do it (cost me $161.30 and I paid through the app). Afterward I let them know that Boombox worked great after rebooting my car and they thanked me for giving them feedback and for being the first customer that my service center has done this to remotely. I already shared photos of my wire tapping and marine speaker that I used here
https://teslaownersonline.com/threa...fit-for-pre-july-19-model-3.20199/post-330990
Here are the messages and invoice
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Here's a highlighted view of where and how I tapped my speaker wires
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Here's how I modified my MPP aluminum undershield to mount the speaker right below where the front motor would be
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Here's how it looks installed. I wanted the speaker raised up to allow water to run out of the hole. My only concern will be if water splashes onto the back of the speaker and pools on there, it could eventually cause mud and dirt to cake on there and freeze the cone in place (causing low volume or no sound). But I have an identical spare speaker that I can replace it with if that happens. If that one eventually fails, then I will order the OEM Tesla speaker and mount in the same spot.