Free Shipping On Orders Over $49. Details

Talk to a Mustang Enthusiast
M-F 8:30A-11P, Sat-Sun 8:30A-9P
$4,500 Giveaway! 3 Winners Enter Now

Raxiom by JL Audio Subwoofer Upgrade Kit (15-20 Fastback w/ Factory Subwoofer)

Item 393867
Call a Mustang Enthusiast at 1-877-887-1105
M-F 8:30A-11P, Sat-Sun 8:30A-9P
Market Price $1,374.99 You Save 13% ($175.00)
Our Price


FREE Shipping

Will this fit your Vehicle?

Select a different vehicle Help?
Update or Change Vehicle
Ship to: Ashburn - 20149
Sorry, please enter a valid US or CA postal code
We're sorry, zip can't be updated at this time.
    Create a list
    Add to New List

    Saved - View your saved items

    We're sorry. We couldn't save this product at this time.

      Review & Installation Video

      Hey, everybody, I'm Justin with, and in this video, I'm gonna be taking a closer look at the Raxiom by JL Subwoofer Upgrade Kit for all 2015 and newer Fastback Mustangs, equipped with a factory subwoofer. Now, in my detailed breakdown, I plan on talking about why prospective buyers might wanna upgrade their factory sub in their Mustang with a 12-inch option here from JL. We'll talk about what's included with the kit along with some of the specs, and then finally, we'll cover a brief, little overview of the installation process. I'm gonna go solid two out of three wrenches here on the difficulty meter due to the light wiring of course, but we will have some more detail on that later on.Now, the JL kit that we have in this video, again, will appeal to those 2015 and newer Fastback owners who have the Shaker Pro Audio System with the 12 speakers in the factory subwoofer, but feel like the factory sub just tends to fall a little short in regards to overall output or quality. Now, by going with this turnkey system here from JL, you're gonna be replacing that 8-inch factory subwoofer and the 100 watt factory amplifier with one of JL's 12-inch subwoofers and corresponding 500 watt amps. So, in turn, you're gonna be getting a much bigger bass response overall, a lower frequency range, and just a lot more thump, while still essentially maintaining the same amount of usable space in the trunk. And with all that said, I do feel like the biggest appeal with this kit here from Raxiom and JL is the fact that it is a turnkey system, essentially ready to rock and roll right out of the box.Now, could you piece together a different system using different components maybe save a couple of bucks? Sure, but this is a convenience factor, guys, you're getting everything you need from soup to nuts right out of the package. Yes, you gonna be spending a little bit more money for that, but you are getting quality components in return, and again, this thing is ready to install the moment you unbox it. So, Ford has been using their patented Shaker system for pretty much as long as I can remember, and for the most part those higher end Shaker offerings do produce enough sound and enough bass response to satisfy most owners. However, like anything in the aftermarket, some people just aren't satisfied with that and are looking for ways to improve with what the factory gave them. And that's pretty much what this kit will appeal to.Now, I can personally attest those factory Ford subwoofers do leave a lot to be desired, especially if you like a more bass heavy listening style. Now, the problem is outfitting or upgrading the subwoofers without totally dominating the trunk space like those old bandpass boxes back in the day, but still at the same time providing you with enough low end response or bass to round out the other 11 speakers in the 401A Shaker Pro package. So, Raxiom JL, they put their heads together, came up with a solution for that problem and that's what we're looking at here today. But, let's break down the individual components here of the upgrade kit from JL and Raxiom, and the star of this kit, at least in my opinion, is no doubt gonna be the JL 12 TW3 subwoofer, which is just a massive upgrade over that 8-inch factory paper cone woofer in every single way.Now, what makes the TW3 really special is that it produces a fantastic bass response, but it's still very shallow or very thin. In fact, this speaker itself is only 3.5 inches deep. So, that makes it very appealing to throw in tight spot like this because, as you can see, it really doesn't need a massive enclosure to sound really good. So, how did JL accomplish this with their TW3 line up? Well, they basically took a traditional woofer and just turned it inside out. And what I mean by that is, if you can envision a speaker, if you ever seen one outside of an enclosure, you know you have the cone and then the skeleton or frame, then hanging off the back of the speaker

      Product Information

      Features, Description, Reviews, Q&A, Specs & Installation


      • Raxiom Subwoofer Upgrade Kit by JL Audio
      • Delivers Deep, Powerful Bass
      • 12TW3-D4 Stealthbox Subwoofer
      • JL Audio JX500/1D Class D Amplifier
      • All Cables and Connectors are Included for a Hassle Free Install
      • Fits 2015-2020 Fastback Mustangs Equipped with the Optional Factory Subwoofer


      Raxiom by JL Audio. The optional eight-inch subwoofer that Ford offers for the S550 Mustang is okay, for a factory part, but it could sound so much better. That is why Raxiom turned to JL Audio to help them create a much needed upgrade/replacement kit. Working closely together, Raxiom and JL Audio hand picked the correct components to replace your Mustang's subwoofer to really bring your stereo system to life. By utilizing a Stealthbox Subwoofer and a Class D Subwoofer Amplifier this Upgrade Kit will deliver deep, powerful bass that will easily rival other high end sound systems.

      Stealthbox Subwoofer. Raxiom's Factory Subwoofer Upgrade Kit includes JL Audio's 12TW3-D4 Stealthbox Subwoofer. The Stealthbox Subwoofer is a direct fit replacement upgrade for your optional factory installed trunk mounted Subwoofer. The Stealthbox features an all-fiberglass, sealed enclosure design that is equipped with JL Audio's revolutionary 12TW3 thin-line subwoofer.

      JX500/1D Amplifier. To boost the power of the Stealthbox Subwoofer Raxiom chose JL Audio's JX500/1D Amplifier. This Amplifier employs a highly-efficient Class D design with a MOSFET power supply to deliver a strong 500 watts. Featuring a variable bass boost at 45 Hz with up to 12 dB of boost, this JL Audio Amplifier is configured as a low-pass filter with continuously variable cutoff frequency selection from 50-200 Hz. Dedicated hi-level inputs are included, in addition to conventional low-level RCA inputs. These inputs make it super easy to install the JX500/1D Amplifier to your original factory head unit.

      Application. This Raxiom by JL Audio Subwoofer Upgrade Kit is designed to fit 2015 to 2020 Fastback Mustangs that are equipped with the optional factory subwoofer only. Does not fit convertible models.


      Fitment: 2015 2016 2017 2018 2019 2020 Details

      MPN# 393867

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (6)

      Write a Review

      Ratings Summary

      4.8 out of 5 overall rating from 6 customers

      • June 22, 2018

        5 2018 GT - Liue813

        Luie 18 GT

        This is the best thing for the my car the saund is very good I know the pice is a lot but I’m happy

        Helpful (6)
      • April 21, 2018

        4 2016 EcoBoost - KrisB


        This combo is the perfect amount of bump for the average person. At first I rode with the rear seat down but it ended up being too loud and the contact between the back cushion and bottom cushion creates an ugly dent in the back cushion. I have zero install experience in audio installs and I was able to pull it off. Getting the box to line up with the bolts is a pain so be ready to leverage it with a crowbar. This kit also works for cars without a factory sub because mine didn't have one. I gave 4 stars and not 5 because of the price.

        Helpful (7)
      • June 30, 2017

        5 2016 GT - Mustang

        12" Sub

        Fits perfect in the truck, sounds wicked, and is an easy install if you have any experience installing stereo equipment.

        Helpful (9)
      • February 16, 2017

        5 2015 GT - JeffA

        Worth every penny.

        Tight clean bass. No way to even compare it to the factory 8 in. It will not blow your ear drums but you can feel and hear the bass. This will make the factory shaker system complete. One recommendation take 1 step up on the jl amp as this jx500/1 is not enough to get full capability out of the sub.

        Helpful (15)
      • November 15, 2016

        5 2016 GT - Zachs197

        Hard hitter

        This sub is awesome it's way harder than the factory system really makes music way more enjoyable

        Helpful (10)
      • November 14, 2016

        5 2016 GT - Miike96

        Wow! Sound is amazing!

        Makes my radio sound great! Installation was easy and worth it. Sound is way better! Better on my gt!

        Helpful (11)

      Questions & Answers (14 answers)

      5 Top Rated Questions

      Will this work for a convertible

      2019 mustang GT. Basic 6 speaker factory stereo. Will this kit work properly?

      • As the base system does not include the optional factory subwoofer, this would not fit your vehicle.

      Helpful (0)

      Curious to know does it only come with one side only? And can we add another one for the other side to have two instead of one

      • This will only come with one side. Two can be bought but custom modifications would need to be done to mount the speaker.

      Helpful (0)

      Do you sell a Audio Subwoofer Upgrade Kit that will fit a 2017 Mustang Ecoboost CONVERTIBLE?

      • At this point in time,we only carry this part for the Fastback models with the factory Subwoofer. 

      Helpful (0)

      what sound system upgrade can I get if I didn't get the factory subwoofer?

      • This kit here would be for the factory base stereo(without a subwoofer) Once that is installed it you can then add the subwoofer kit here.

      Helpful (0)
      Post Your Question
      9 More Questions
      Is everything needed to install included? I have a 17 gt with shaker pro and just want to upgrade the dub. 1 answer
      Why would this system not work for a 15-17 fastback with shaker stereo but no subwoofer in package? To my understanding trunks are identical and box should fit right in. As for amp and wiring, well self explanatory. 1 answer
      Hey guys so wondering about this package right here was wondering if this will fit my 2017 Ford Mustang V6 looking into adding sound system and was wondering if this one would do fine on mine please let me know when gladly appreciate it? Thanks 1 answer
      Will this work on a 2015 GT convertible with the Shaker Pro system? I have the factory trunk mounted sub on the right inner quarter. 1 answer
      Hi, have only 8 speakers I can add this subwoofer or no 1 answer
      Is there an aftermarket sub woofer kit available for my 2017 Aussie built Mustang GT coupe, that did not come equipped with (or was made available) a subwoofer system? I'm sure there are plenty of us down here that would like to have a decent sound system that fits! 1 answer
      Hi, I'm not sure if there are any other subwoofer audio system options on the 15-17 Mustang, so I just want to ask upfront: will this be a good direct replacement for the terrible one that comes with the full Shaker System option? Thanks, Kat 1 answer
      Will the subwoofer kit come with two subwoofers or one 1 answer
      will this fit my '16 Ecoboost premium coupe that doesn't already have a subwoofer. Or is it only to replace an existing subwoofer setup ? 1 answer

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Class D Subwoofer Amplifier
      • (1) Stealthbox Subwoofer
      • (1) Remote Bass Control
      • XD-MFB-MAXI Fuse Holder with Genuine 30A Maxi® Fuse
      • 17 ft (5.18 m) Red 30A Core Power Wire, terminated with ring
      • 3 ft (0.91 m) Black 30A Core Ground Wire, terminated with ring
      • 17 ft (5.18 m) Blue Remote Turn-On Lead Wire
      • 25 ft (7.62 m) Blue Speaker Cable
      • XD-CLRAIC2-18 2-channel, 18 ft. (5.5 m) Audio Interconnect Cable
      • Self-Tapping Ground Screw
      • Rubber Firewall Grommet
      • Nylon Wire Ties
      • Hex Wrench for Fuse Holder

      Will It Fit My Mustang

      • Bullitt - 19, 20
      • EcoBoost - 15, 16, 17, 18, 19, 20
      • GT - 15, 16, 17, 18, 19, 20
      • GT350 - 15, 16, 17, 18, 19, 20
      • GT350R - 15, 16, 17, 18, 19, 20
      • GT500 - 20
      • V6 - 15, 16, 17

      Fits Fastback Mustangs that are equipped with the optional factory subwoofer only. Does not fit convertible models.

          Related Mustang Categories