Upgrading the Gladiator’s Audio with JL and Garmin

Chris Hamilton . November 06, 2025 . Department . Chris Hamilton

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Jamming Out in Our Jeep

Continuing on with our American Gladiator series, this issue, we turn our attention to in-cab entertainment. The audio setup from the factory is good in the sense that it surrounds you fully, but it’s extremely limited in quality and performance. The truck comes with some dash speakers and overhead mid-range units, but the lack of bass and clarity leaves you needing more, especially when driving with the top off or hanging out at the beach. So, we turned to one of the best names in the business to upgrade our audio system. You may know JL Audio as a top-tier speaker manufacturer, but were you aware that they have recently been acquired by the biggest name in navigation—Garmin Ltd.?

Garmin has been building the best products on the market for years, and its quality standards are second to none. When we heard it had taken the reins at JL Audio, we knew that this amazing car audio brand was going to get even more impressive. The JL Audio brand is here to stay, but with the engineering and product development power of Garmin in the mix. The consumer is the real winner at the end of the day. Not only does JL offer the best speakers and preassembled subwoofer boxes on the planet, but it also has all the amplifiers to power them, as well as the connectors to make them all work flawlessly.

So in this issue, we go through the parts we picked and the steps it took to install them. We even added a high-quality HD dash cam in the mix while we were at it. The install went exactly how the instructions said it would, and the sound quality is the best we’ve heard in a Jeep Gladiator without building a bunch of custom panels or boxes. So let’s jump right into the assembly and let the music play.

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SOURCE

Garmin
913-397-8200
www.garmin.com

The first thing we are going to focus on is the low-frequency audio signals coming from the factory head unit. Also, this rear seat appears to be the perfect spot to hide some big bass speakers.

This JL Audio Stealthbox packs dual 10-inch thin-line subwoofers into a sealed box designed to drop snugly under the rear seat of 2020‑up Jeep Gladiators, delivering deep bass without wrecking your floor space.

This Class‑D amp cranks out 100W × 4 channels for our midrange speakers and a beefy 500W for our subs, with impressive tech features like single-cycle control, a voltage regulator, and top-tier efficiency to keep heat and strain in check.

To wire this system up, we installed this 1/0 AWG power and ground cable kit that is designed to run dual amplifiers with minimal voltage drop, plus distribution-ready lugs, a distribution block, and a fuse holder to keep our system safe and solid.

Adding this LoC‑22 will convert our factory speaker-level signal into clean RCA outputs, letting us plug in aftermarket amps without pulling our stock head unit or losing audio quality.

The first step of the install was to remove this plastic barrier under the rear seat using a 10 mm socket.

This piece will not be reinstalled, so it’s headed to the storage unit.

We could then line up the new brackets provided with the Stealthbox to our factory seat bracket bolt holes.

After confidently lining up the left and right brackets, we bolted the brackets to the JL Audio speaker box with the supplied hardware.

Here, you can see the brackets installed on the box before it is installed in the truck.

Next, we placed the box into position, and the bolt holes lined up perfectly. This is a very well-engineered unit.

Here you can see how it clears the plastic box that holds the roof bolts when we remove the top. Everything fits as advertised.

With the seat bottom lowered, it’s clear that a lot of time and effort went into the design of this box. It fits so perfectly.

Now that the easy part was done, it was time to start the power portion of this install.

The box is designed with space to mount the amplifier right on top. No more building amp shelves or custom brackets!

Next, it was time to get the wiring installed. This kit from Garmin/JL Audio comes with everything we needed to get the sound to the subs.

To grab audio and remote signals, we jumped online and found the exact color within the B-panels of our truck. Do your research, and you’ll find that it’s a simple splice. Don’t overthink it!

We used this Garmin/JL Audio line-out converter to convert our factory speaker wire signal into RCA cables for the amp inputs. This LoC did not need a remote wire, as it detects turn-on through the speaker signal, but we added a remote wire anyway since it was easy.

The RCA cables could then be plugged into the amplifier, and speaker wire could be run to the terminals built into the speaker box.

Here is the completed install of our JL Audio Stealthbox in our 2020 Jeep Gladiator. It was a clean and simple install!

To protect our goods when we are not in the truck, we decided to add a Garmin dash cam. Bonus: we can also record inside and outside of the cab while driving in case a crazy incident happens.

What makes this dash cam super easy to install is the OBD port connector.

We simply popped off this dash cover and connected the OBD connector to the dash cam USB wire.

We also needed to unbolt the grab handle on the A-pillar to run the dash cam USB wire.

The install went exactly how the instructions said it would, and the sound quality is the best we’ve heard in a Jeep Gladiator without building a bunch of custom panels or boxes.