I haven't seen much on adding a sub to a 2020 Traverse so let me provide what I can. First off this project sucked so much! I've installed subs before but never in a new car. Anyways at this current time there is no aftermarket radio or amp pro for a pre amp signal ( that i can find) so I went with a Audio control LC2i. I did find that Axxess makes a harness for other Chevy vehicles that I used to create a T harness so that I didn't have to tap into any existing speaker wires. (Axxess AXEXH-GMLN31) this is a 48in harness extension used for a data interface for newer Chevy cars but Traverse isn't listed I took a chance on the harness and it paid off. So I got the harness and began cutting I spliced into the front 2 speakers and added about 10ft of wire from the front right and left positive and negative. I took out the radio and connected to the harness. To get the radio out it's just clips get a panel tool and pry up carefully or just pull the entire bezel including vents will pop out. I ran the wire through the dash and down the driver side under the panels and carpet. If you decide to just tap the speakers it's the yellow and yellow black for driver side and the blue and blue black for passenger (this will be on the grey plug) If you get the harness its normal colors, white and grey (also on the grey plug..obviously). At this point I had my 2 speakers that I would use to create the signal for the LC2i I did not get a remote wire I opted to use the GTO feature of the LC2i and it works perfectly. Next I ran a power cable on the driver side under the panels and I went through the firewall at the same spot as the factory harness I drilled through the groument and pulled the cable through and sealed it with black rubber sealant. I took out the first row back seat the long side and mounted the amp under the seat I used the seat belt bolt as the ground for the LC2i and amp. I unbolted it cleaned the surface with a wire brush and screwed it back down. I added a piece of 12 gauge wire to the end of the power cable in the reducer to run from my amp to the LC2i. I then ran a cable from the remote out of the LC2i to the amp. At this point I had all my connections. 2 speakers, power and ground for both devices and remote turn on. I mounted everything to a piece of 1/8 inch abs and I cut a u shaped slot in the carpet to run the wires through and some zip ties. I had to order some wire reducers because I ran 0 gauge wire and the amp only uses 4 gauge. I did this cause I may upgrade later. After install you'll need to disable the ANC mics by unplugging all 4 in the headliner. I searched online all over and I couldn't find where the module is. Trust me it's not the same as the 2019 I checked under the dash. Take out the headliner handles and pull down slightly, reach in there and unplug them. All 4 will need to be unplugged above each seat. I used a flat head to pull the red clips I'll post pics of the ANC mics. This doesnt bother the Bluetooth mic that is in the console where the lights are by the mirror. I personally haven't noticed a difference on the freeway since disabling ANC specially since I have some bass to drown it out 🤘. More pics coming