I recently finished up my Bose Subwoofer replacement in my 2016 LTZ. I felt the Bose Sub was very underwhelming. I considered the Kicker option made specifically for the Silverado, but didn't want to give up the floor space. After removing the center console and lots of measuring, I came up with a box design to work with the JL Audio 8W3V3-4 8" sub. This sub requires a volume of 0.30 cf. short of making a fiberglass box, I'm convinced there is no way to get any more volume from a box that fits under the center console (with no modifications to it).
I added an Alpine MRV-M250 amp to power the sub and mounted it on the back wall next to the factory amp. Also got the remote for the amp which is mounted inside the large storage compartment of the center console.
It sounds absolutely amazing, exactly how the factory high end system should sound! You can feel the bass in the seat, something that never happened with the stock sub!
Here's a few pictures.