Free Shipping On Orders Over $49. Details

Talk to a Mustang Enthusiast
M-F 8:30A-11P, Sat-Sun 8:30A-9P
Win $5,000 For Your Mustang! Enter Daily
Win An Eibach Sportline Kit! Enter Daily

X-Force Varex Smartbox (15-20 All)

Market Price $399.00 You Save 10% ($39.90)
Our Price


FREE Shipping

  • Item 393960

Will this fit your Vehicle?

Change Vehicle Help?
In Stock Ships same business day.
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.

    Features, Video & Details

    • Adjust Sound of Exhaust System
    • Use via Bluetooth® on your Cell Phone
    • 2 Mode Options
    • Designed for Unobtrusive Placement
    • Easy Installation
    • Compatible with Many Varex Mufflers and Valves
    • Fits all 2005-2020 Mustangs with Varex mufflers or Exhaust Valves

    Review & Installation Video

    Review & Install Video

    Hey guys, Stephanie with here with a review and an install of the X-Force Varex Smartbox, available for all 2015 and newer EcoBoost and GT Mustangs that have the X-Force exhaust system installed. We're gonna be talking about a few different things with this Smartbox today, we'll mainly talk about what exactly this piece is, what it does, and the install. The install for this is easy, it's a one out of three wrenches on the difficulty meter, but I'll get more into that later. You should be checking out the Varex Smartbox from X-Force if you have a Varex cat-back for your S550 GT or EcoBoost and you want a greater ability to change the sound and loudness of your exhaust on the fly, the one thing included, key fob, gives you. So X-Force makes an exhaust called the Varex, and it's a tunable exhaust that comes with a key fob. When the user presses the button on the fob, the exhaust valve will move or tune until the button is released. This allows the user to make the exhaust as loud or as quiet as they want to. Now, unlike those traditional cutouts that are generally fully open or fully shut with no options in-between, Varex gives you the option to customize your sound with the level of adjustment, essentially giving you five different mufflers in one, as Varex puts it. This is achieved by opening the butterfly valve in different increments, changing the tone slightly along the way. This works to change the tone and all, but you aren't able to precisely control the valve position, and there's no feedback of what exactly the valve position is. You'd have to guess. And there isn't any memory on the valve position either. This Smartbox changes that. It allows you to create presets and monitor exactly the valve position, so you know where you like your settings. It also has some preset valve options for you as suggestions, so you can just hit a button and quickly change your exhaust tone. The preset positions are closed, 25%, 50%, 75%, and open. But if you don't like these preset options, you do have the ability to customize them to your liking. The Smartbox also has a matrix mode as well, which will allow you to program a setting that'll automatically change the valve position while you're driving. You can create parameters around the valve ranges, like RPM, throttle position, and speed. Now you can get crazy here and really customize your exhaust. There really isn't anything else on the market like this. This is really technical and involved if you want it to be or simple if you just wanna stick with normal settings. But you can get really in-depth here. So we've discussed manual mode and matrix mode, but this also has a geo mode as well. Geo mode lets you change the sound of your exhaust automatically according to your location. You're gonna find a region on a map and then set a particular exhaust sound for that region, and the Smartbox will automatically change for the sound for you while you're in that region. All you have to do is make a circle on a map on your smart phone screen to set the region. So the way this all works is through an app that links to your smart phone. You'll be using your phone to customize everything and set up these parameters, so you won't have an entire device with a screen to locate in your interior, you just connect to your smart phone. I like this because you aren't burdened with trying to find the location for a screen, and you can just adjust things as you like to. You're gonna get your control module and a power cable in the box, along with an OBD2 cable, but you'll also have to download the app as well to have full access into this. When it comes to price, I will say right now that this is technical and there's nothing else like it. You can expect to spend between $300 and $400 for this Smartbox. But also keep in mind that it needs to be used with the X-Force Varex cat-back. I will agree that this is a little pricey, but it's not like you have to buy it at the same time as the cat-back. You'll be able to make your own custom exhaust sound with this device, which is pretty neat. As far as the install, everything is completely plug-and-play. You can expect to spend about a half hour, tops, since you'll be tucking away some cables. And this is gonna be a one out of three wrenches on the difficulty meter. You're gonna connect your OBD2 cable to the port, plug in to your control module, which can be hidden anywhere in the car, you tuck away your cable, and run your power cable to the Smartbox as well. The power cable runs to the motor on the mufflers, and then you just need to tuck away all the cables to your liking. It doesn't get much easier than that. Wrapping things up with the X-Force Varex Smartbox, this is an incredible piece of technology designed to be used with the Varex cat-back exhaust. It allows you to fully and automatically change your exhaust tone depending on a number of factors, and it's used through your smart phone screen. As always, I suggest you check this thing out more online for yourself. And for all things Mustang, keep it right here at

    Noise Control In Your Hands. There's nothing quite like the roar of a Mustang's performance exhaust system. That is until you're driving downtown late at night or you're five hours into a road trip with a headache. The X-Force Varex Smartbox allows you to adjust the noise of your exhaust system. All you need to do after installing the Smartbox is use a simple smart phone app via Bluetooth.

    Adjustability for Enhanced Oversight. An improvement upon previous FOB exhaust noise adjusters, this smart phone system features 2 distinct modes to give you greater control. The manual mode enables precise adjustment of Varex valve positions in the exhaust. You can create custom presets in this mode. X-Force Varex Smartbox also includes the matrix mode, which provides real-time, automatic control of the exhaust valve positions. The matrix mode utilizes information about the RPM, throttle, and speed to adjust automatically.

    Hidden Power. Sleek but durable, the X-Force Varex Smartbox can be subtly tucked away in the cabin wherever you would like. The power and OBDii cables can be hidden under carpets and even inside some inner panels to conceal the set-up of this useful control system.

    Application. The X-Force Varex Smartbox is intended for use on 2005-2020 GT and V6 Mustangs. The smartbox is compatible with most, but not all Varex mufflers and exhaust valves.

    Fitment: 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 Details

    MPN# 393960

    CA Residents: WARNING: Cancer and Reproductive Harm -

    What's in the Box
    • (1) Smart Box Control Module
    • (1) OBDII Cable
    • (1) GPS External Antenna
    Installation Info
    Tech Specs
    Will it fit my Mustang?
    • Boss 302 - 12, 13
    • Bullitt - 08, 09, 19, 20
    • EcoBoost - 15, 16, 17, 18, 19, 20
    • GT - 05, 06, 07, 08, 09, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20
    • GT350 - 15, 16, 17, 18, 19, 20
    • GT350R - 15, 16, 17, 18, 19, 20
    • GT500 - 07, 08, 09, 10, 11, 12, 13, 14, 20
    • V6 - 05, 06, 07, 08, 09, 10, 11, 12, 13, 14, 15, 16, 17

      Customer Photos

        Questions & Answers (7)

        5 Top Rated Questions

        I have a X-Force Twin 3in Stainless Steel Turbo Back Varex System in my 2015 ecoboost mustang can I add the smartbox to my system?

        • Yes, the X-Force Varex Cat-Back Exhaust is indeed compatible with the X-Force Varex Smartbox. I will post the link to the cat-back below:

        Helpful (1)

        if I were to buy the Varex hidden motor muffler(s) and install them on my 88 GT, is there any way I could complete the system with this item. I have extremely loud exhaust, and would like something to quiet it down on long drives such as this. If not what would be a better item to buy rather than changing my exhaust set-up.

        • This will be compatible with the Varex Hidden Motor mufflers.

        Helpful (0)

        Is this compatible with the vk12 kit?

        • Unfortunately, this product is not compatible with the X-force exhaust cutouts. This smartboxwas designed to work with the X-force exhausts.

        Helpful (0)

        Do you need a smartbox per exhaust muffler?

        • You will only need one X-Force Varex Smartbox per axle back.

        Helpful (0)

        Do I have to make connections to the muffler from the box? Are there directions that come with the box?

        • The box will be connecting right to the muffler, and the Box will have wires leading to your ODBII port. You will receive directions with the package, however take a look at the product video we have and it may help visualize the install.

        Helpful (0)
        Post Your Question
        2 More Questions
        Does this tune the exhaust note, as in deep vs raspy, or does it just tune the volume, loud vs muffled? 1 answer
        what exactly does this do to a factory mustang 1 answer

          Customer Reviews (6) Write a Review

          Overall Rating 4.8

          out of 5 stars

          Installation Time:Afternoon

          • Loudness / Volume 4.666667 4.7
          • Exhaust Note 4.666667 4.7
          • Fit & Finish 4.833333 4.8
          • Bang For Your Buck 4.5 4.5

          • 5/5

            Installation Time: Less than 1 Hour

            May 21, 2019

            Nice Sounds

            This was an easy install over the Varex system. I really enjoy the added sounds to my exhaust.


            Year: 2015 Submodel: EcoBoost

            Helpful (1)

          • 5/5

            Installation Time: Less than 1 Hour

            December 30, 2018

            Great addition to XForce Varex Exhaust

            Great addition to the XForce Varex exhaust system. Works great.


            Year: 2017 Submodel: GT

            Helpful (2)

          • 5/5

            Installation Time: Afternoon

            August 22, 2017

            X-force Varex Smartbox

            Well made control box very easy to set up and use but no instructions for the installation


            Year: 2016 Submodel: GT

            Helpful (12)

          • 5/5

            October 18, 2016


            Perfect for daily drive and you can make it louder for show whats best than that , no more tickets for having loud exhaust!!


            Year: 2016 Submodel: Other

            Helpful (14)

          • 5/5

            October 18, 2016


            Gonna hook it up looks great if you don't have one get one asap


            Year: 2016 Submodel: V6

            Helpful (14)

          • 4/5

            Installation Time: Afternoon

            October 18, 2016

            Works well with the varex system

            Works well no issues so far . Varex system is the only way to go if you want quality and adjustability


            Year: 2015 Submodel: GT

            Helpful (16)

          Related Mustang Categories