I installed their kit for a 2020 Model 3 SR+ as well, and the results on my 2021 SR+ were on par.
I would recommend plugging everything in first before running your wires through the center console to test the audio first.
The only difference from the pre-2021 update is the missing front signal plugs (previously a more square shaped plug, and has been replaced by a red and black wire for each side of the vehicle. The instructions specify which wires to plug into. They share the same existing wire and for driver’s side, you match the black with black wire, and red with purple wire. For the passenger side, you just have to match the red with red wire, and black with white wire. Once everything was tested, I ran the wires under the carpet along the dip in the floor. There is enough of a gap beneath the carpet to not feel the wires through the carpet.
As expected, the front tweeters and mids were activated and produces audio that feels more immersive than the speakers closer to the windshield and in the door. The rear deck is missing speakers, although I connected the harness to it so the wiring was complete and neater. (No adverse effects as a result) I tested the left to right channels in the audio settings and everything was correctly functioning.
Shipping took about three weeks to reach me in Hawaii. It did travel to the continental US before heading back to Hawaii.