I got my idea and most of my info from @67L48 so to see the original post look at his in depth write up.
I will say it is a definitely an upgrade from factory but don’t expect the low end deep bass if that is what you are looking for.
My material list:
KICKER 48CWRT82 8” 2ohm subwoofer.
KICKER CXA400.1 amp with 8AWG wiring kit.
KICKER 46KSIL RCA adapter.
KICKER 46CXARC remote.
5 pack of CANOPUS 50mm 5sqft sound deadening mat.
1 10 ounce bag of poly-fil.

Everything above is from Amazon.
I also had to grab.
1 12x18x1/4 MDF board
1 8” corner brace
1 tube of clear silicone
From Home Depot.

I first measured and cut my MDF to size for mounting the amp and cut 6” off one side of the corner brace to make a vertical support for my amp board. This will mount with one of the sub box studs.



I then mounted my amp with the adjustment ***** facing up on the board.
I removed the sub box and removed the factory sub. I took the factory wiring from the sub and cut it close to the sub and wired up the RCA adapter.

I filled the box with the whole bag of poly-fil.

I wired my subwoofer down to 1ohm per KICKERS website and ran the speaker wires out of the box and siliconed the wires where they come out of the box. I installed the subwoofer and used all of the sound deadening mat from Amazon to wrap the factory box.

This is just the beginning of wrapping the box there is more than enough sounds deadening mat in the box to completely cover the box front and back. I then test mounted my amp and cut a small slot in the insulation on the back wall of the cab to be able to run my RCA cables from the factory sub harness behind the insulation and to my amp. I ran all my wiring on the passenger side of the truck besides the remote wire for the adjustment **** that I ran up the driver side and under the dash to mount my adjustment **** under the steering wheel.
The amp dose not take a remote wire like most other amps, it receives power from the RCA cables and turns on with the radios.
I am technically over powering this subwoofer when wired down to 1ohm with the amp but for a total of close to $450 this is a pretty good set up for replacing the subwoofer and keeping the factory location and box.
This set up will give you more punchy bass and more low end than the factory B&O system.
If you have any questions I will try to reply and answer them the best I can.

This is the final product.

 

if you are within your return window for the speaker I would recommend a woofer with a higher sensitivity than 81db and a lower frequency response than 30.
from google


The KICKER 48CWRT82 is an 8-inch, shallow-mount subwoofer from the CompRT series. Designed to fit easily under seats or in tight spaces, it features a dual 2-ohm voice coil setup that offers great wiring flexibility.Core SpecificationsSize: 8 inchesImpedance: Dual 2-ohm voice coilsRMS Power Handling: 300 WattsPeak Power Handling: 600 WattsFrequency Response: 30 Hz – 500 HzSensitivity: 81.8 dB (1W/1M)Mounting Depth: 2-11/16" (approx. 6.7 cm)Mounting Cutout Diameter: 7"Box/Enclosure RecommendationsSealed Box Volume: 0.2 to 1.0 cubic feet (5.6 - 28.3 Liters)Ported (Vented) Box Volume: 0.8 to 1.2 cubic feet (22.7 - 34.0 Liters)Key Technologies