Thanks for the info. Based on some of the reviews out there, it seemed like the door speakers plus a subwoofer was the best combination if you had the standard audio.
Oh no, the subwoofer is ridiculously overpriced. You can get a much better sub from Sound Qube for $100 that is basically a drop in replacement... but to take advantage of it, you'll need an amp, otherwise it's weaker than the stock sub.
HDS208 Dual 2
They have sales pretty often, so you can get it for less than listed there if you wait around.
The door speakers, as I said, don't really add much, if anything, to the soundscape inside the car, I would definitely skip those. A sub and amp will be your best bang for the buck. The problem with doing amps in the Tesla is the door speakers are all 1 ohm, so you need a sub that's stable at 1 ohm and that's hard to come by, other than the LH amp.
Otherwise, yeah, you have to replace your speakers along with the sub and go aftermarket traditional amp. You can get much cheaper, better door speakers from the usual car audio suspects than the relatively generic LH ones.
In the end, if you don't want to go the LH way, get a traditional 5 channel amp, a wiring kit (or custom loom) to output to the doors and sub from the Tesla harness. The advantage of the LH amp is that it's plug and play and easy to DIY. The disadvantage is QA (high probability of multiple failed amps) and insanely long RMA time, coupled with spotty communication.