Here are the mods that I have done, in order, on my late 2014 model S with 85 kWh battery, base stereo, tech package, adjustable suspension and pano roof.
0. Eyeball mirrors to both side mirrors $5. Floor mats from O’reilly $40
2. Rear subwoofer $160 from crutchfield, left rear trunk pocket. Power from 12v auxiliary. Signals from front door speakers – wire colors are below. They are different colors than earlier vehicles on the right side.
3. Hooks and suction cups to hold license plate without drilling holes.
3. Eco hitch $175 from torklift central in Washington state – installed by midnight trailer in redwood city, CA. Fits under the bumper with no drilling.
4. Trailer wire isolation circuit to power the trailer lights without drawing from tesla circuits. Took lots of experimenting by Midnight trailer and me. Power from auxiliary socket, with a switch to toggle the 12v between woofer or trailer. (No woofing and trailering at the same time.) Limit is 15 amps and both devices are subfused at 10 amps. The right and left signals come from the side marker lamps. The brake signal comes from the rear hatch brake light bar. Oddly, the left blinker illuminates all the rear lights unless the headlights are on, but I don’t mind driving w headlights on when trailering.
5. Upgraded rear door speakers to infinity $160 online. I used the tesla speaker holders but you can use adapters if you don’t want a slight bulge at the bottom of the doors.
6. MyPod trailer from little guy trailers in Ohio $10k via greg at Bretz RV in Montana. Custom painted tesla white. Base model as I didn’t need a TV or speakers, and I can add AC later if needed. I had to adapt the trailer 7 pin to the trailer light 4 pin and buy a 3 inch rise trailer bar. Multiple trips to walmart and autozone in Gillette WY. Getting plugged in to charge sometimes requires removing the trailer.
7. Wired spare tesla camera for rear view behind the trailer. It’s great having the high def display on the screen. Only hard part is disconnecting the camera wires inside the hatch. I plan to get a one foot extension to make it easier to reach.
8. Lots of adapters
9. Front lighted T emblem. Purchased from Evannex. Designed by Rick H. et al at tesla motors club.
With the positap connectors, the cone can be removed and the T left in place.
Below the LED blinking effects module ticks into the hole on the left driver’s side. The red/black wire going to the right is the blue LED tucked into he dash so you can see the T flash rate.
View of OBD port with adapter plug. I covered the exposed pins with electrical tape.
10. Dash cam. Mini 0806. Small, inexpensive camera. Great video. Sometimes flaky. Have to cycle it to on a lot. This may be b/c I leave it running.
11. Lighted rear T. I added another blinker circuit, wired the brake light input, and powered from the license plate light.
I reached in from the bottom of the hatch so I would not have to remove the large cover. The blue brake light is accessed from the right corner bundle of wires.