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MMD V-Series Side Exit Cat-Back Exhaust w/ Rocker Panels (15-17 GT Fastback)

Market Price $1,229.99 You Save 18% ($220.01)
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    Features, Video & Details

    • MMD V-Series Styling and Aggressive Flowmaster Sound
    • Durable, Lightweight Thermo-Formed ABS Side Skirts
    • Cat-Back Features 2.5 inch 409 Stainless Steel Tubing
    • Includes Scavenger X-Pipe and 2 Flowmaster Mufflers
    • Black Coated Dual Side Exit Stainless Steel Tips
    • Rear Bumper Filler Plates Included
    • Fits 2015-2017 GT Fastback Mustangs

    Review & Installation Video

    Review & Install Video

    Hey guys, Stephanie with, and this is my review and then install of the MMD V-Series Side Exit Cat-back that comes with a new set of Rocker Panels fitting your 2015 and up GT Mustang. We're gonna be talking about a few different things with this exhaust today, but mainly we'll talk about the sound of the cat-back and the install. The install for this is easy, it's a one out of three wrenches in the difficulty meter, even though there is something a little bit different with this cat-back but I'll get more into that later. The V-series cat-back from MMD is gonna be for the S550 GT owners out there that are looking for something different and outside of the box. It's gonna be for someone looking for a loud and deep tone with a soft hint of raspiness to it for someone that's looking for something visually different. This is a perfect option for the guys that are looking for something aggressive and loud. This cat-back is going to eliminate the factory resonator and replace it with a Resonator Delete X-Pipe that leads down the high flow straight through Flowmaster Mufflers. And this setup is gonna give a sound that I consider to be one of the louder options as you guys already heard from the sound clips. So, basically what's happening here is that MMD took their knack for a different styling and worked with Flowmaster to create a cat-back that has both visual style and a great sound. We talk about sound first and style second. Like I mentioned earlier, this cat-back is going to eliminate the restrictive factory resonator and replace it with an X-pipe. Now, an X-pipe typically makes for a louder system that'll produce more power later on the RPM band than an H-pipe would. X-pipes are generally raspier as well, and they force the exhaust to cross streams to even out flow. I'd say that this system has muffled raspiness to it. This is obnoxiously raspy because the mufflers calm it down. Removing this resonator is going to have a bunch of performance benefits. We'll get sound and power improvements and even some weight benefits since a simple X here is gonna weigh less than the factory resonator, and that's just a nice little bonus that you get from swapping over to an aftermarket system like this one. The cat-back is gonna keep the two-and-a-half-inch diameter, and you're also looking at a full stainless steel mandrel bent cat-back with this system with black coated side exit stainless steel tips. As always, the main component of a cat-back is gonna be the mufflers. They're the heart of the system, and they play a large role in both the sound and performance benefits. In this case, we're looking at a set of high flow straight through Flowmaster Mufflers that give a powerful and aggressive sound from the cat-back. There's a touch of raspiness to this system, but I think it does a good job of balancing volume and raspiness to create a sound that's flattering to the GT. The first impression that I got from this cat-back is that it has a deep and loud sound. I know you can hear the cat-back is deeper than the factory exhaust, and as you start climbing the RPM, I don't think the deepness of the tone goes away. It definitely reminds me of a muscle car tone, but what's nice is that it keeps the loudness without getting distorted like a lot of other systems tend to do. I don't hear any sound distortion with this cat-back, which I thought I might considering the X-pipe and the louder volume level. I'd place this cat-back towards the top of the pack when it comes to volume. It's not a quiet cat-back by any means. It's actually on the louder side in my opinion. Call it a solid four on the loudness meter with one being very quiet and five being the loudest out there. If you're not looking for something this aggressive, then there are a ton of other cat-back options on the site that you can check out. If we wanna talk about the styling some, you can see right here that this is a different setup. The cat-back starts out normally with your X-pipe that's two-and-a-half inch, sort of bought up to your factory system. Then after the mufflers, it's gonna turn and exit out of the side, right before the rear tire and after the door. Now, because this is a side-exit exhaust, you're gonna need some new side skirts to work with this. MMD has you covered though. It include side skirts that are gonna go over the top of your factory side skirts. MMD calls these side skirts OEM quality, and I'd have to agree with that after seeing them here and seeing them installed on the GT. These do look OEM. They're made from ABS, and they're an unpainted black. Now, you can paint these if you really want to, but ABS doesn't usually tend to paint the best. And like I said, they do look OEM, so it's not like you have to paint them in my opinion to make them look good. And one other thing that MMD does for you here is they include some block off plates for you. Since your exhaust won't be existing through rear anymore, you're gonna have cut outs in your stock valance that would be empty, which would just look weird. So the block off plates would cover those cut outs. You'd be surprised at how much of a difference his makes styling-wise, and I'm happy to see MMD thinking of everything here and giving you guys a complete kit. When it comes to price, I was honestly surprised, but surprised in a good way. We all know that cat-backs for the S550 are damn expensive, especially for a high-end stainless steel system. With this cat-back coming with the extras of the hardware for the install and the side skirts and the block out plates, I thought it was gonna be even more expensive. You're gonna expect to pay close to the $1,300 mark for this cat-back, which isn't the most expensive cat-back out there. With the sound, the materials and the extras you're getting here, I'd say that this is a good deal. As far as the install goes, even though this is a little bit of a different setup, you're gonna be looking at an easy one out of three wrenches on the scale when we look at difficulty. All that you're really gonna need is a socket set, a drill since there is some small drilling, and a lift would certainly make things easier, but the job can be done on jack stands as well. You're gonna be removing the exhaust from the resonator bag, so an extra set of hands can make things easier for you here. You can start by removing your rear hangers since you won't be needing those anymore any way. Then you're gonna remove the exhaust from the resonator bag, and then once that's off, you're gonna need to address your side skirts. Your mud flaps will come off, and because the new skirts install with 3M tape, you're gonna want to make sure that your factory side skirts are really clean, so you can get a good surface for the tape to bond to. Once the surface is ready, you can install your new side skirts. Next, you'll need to remove your rear wheels so you can get to your inner wheel well. The edge of the MMD side skirt and the factory side skirt will need to be lined up so you can drill a small hole and clip the two together. After that's done, you just have your cat-back to install. You can piece the system together on the car if you want to. So, you start with your X-pipe and then your mufflers. Once you get to the tail pipes, you need to install the hanger mounts on to the hangers. These tail pipes are going to hang from the rear sub frame, which isn't a bad thing, but I will say that this causes the system to be close to the ground and a little low-hanging, so just note to be careful with ground clearance. Once you have the system pieced together and all lined up, you can tighten everything down and you're good to go. Overall, the MMD V-series side exit cat-back is a cat-back that offers both sound and appearance of [inaudible 00:07:18]. This is a loud and aggressive cat-back, and it's gonna replace the factory resonator with an X-pipe that'll ultimately drop some weight and open up both exhaust flow and power. The cat-back features high flow straight through mufflers that produce a good amount of volume and sound without being over bearing. As always, you can check this cat-back out online some more for yourself. And for all things Mustang, keep it right here at

    MMD Styling with Aggressive Sound. MMD worked hard with Flowmaster to develop and create an extremely high quality Side Exit Cat-Back Exhaust that will not only give your V8 powered Mustang a sporty aggressive look, but a deep aggressive sound as well.

    MMD V-Series Side Skirts. Modern Muscle Design manufactures their V-Series Side Skirts from OEM quality high impact thermoformed acrylonitrile butadiene styrene (ABS) plastic for superior durability. These black Side Skirts feature a factory style grained texture for an OEM appearance and to increase longevity against rock impacts from daily driving. MMD V-Series Side Skirts are simple to install using the supplied 3M doubled-sided automotive bonding tape.

    V-Series Side Exit Cat-Back. Manufactured by Flowmaster, this Side Exit Cat-Back is made from 16 gauge 409 stainless steel for superior strength and long lasting corrosion resistance. Featuring mandrel bent 2.5 inch diameter tubing, an X-Pipe and a set of straight through mufflers, this V-Series Cat-Back will significantly out flow the restrictive factory exhaust system for a bump in power. MMD's Cat-Back includes a pair of black coated stainless steel dual exhaust tips that exit through the included side skirts for aggressive looks and sound. This Cat-Back is a direct bolt-on replacement for your Fastback GT's factory exhaust system with no cutting or extra modifications required.

    Bumper Filler Plates Included. When designing their V-Series Side Exit Cat-Back Exhaust Modern Muscle Design thought of everything. MMD includes a pair of stylish satin black block off filler plates to cover the exhaust tip holes left in your bumpers lower rear valance. Seeing that the Base GT and the Performance Pack GT feature different rear bumpers please be sure to select your specific model from the options above when ordering.

    Application. This Modern Muscle Design V-Series Side Exit Cat-Back Exhaust is designed to fit 2015-2017 Fastback GT Mustangs equipped with the DOHC 5.0L V8 Coyote engine. This kit does not fit Convertible models.

    Please Read. If you are having trouble determining what style bumper your Mustang is equipped with please refer to the comparison image above.

    Fitment: 2015 2016 2017 Details

    CA Residents: WARNING: Cancer and Reproductive Harm -

    What's in the Box
    • (1) X-Pipe
    • (2) Mufflers
    • (1) Right Tailpipe Assembly
    • (1) Left Tailpipe Assembly
    • (2) Block Off Plates
    • (1) Driver Side Side Skirt
    • (1) Passenger Side Side Skirt
    • (1) Hardware Pack
    • (4) 2-1/2" Clamps
    • (4) Rubber Mounts
    • (2) 3/8” x 1 1/2” Bolts
    • (2) 3/8” x 1” Bolts
    • (4) 3/8” Hex Nuts
    • (2) 3/8” Flat Washers
    • (4) 3/8” Lock Washers
    Installation Info
    Tech Specs
    Cat-Back Exhaust Specifications
    Piping Material: 409 Stainless Steel Tip Material : Black Coated Stainless Steel
    Piping Size: 2.5" Tip Size: Rectangular
    Muffler Type: Straight-through Fitment: 2015-2017 GT Fastback
    Will it fit my Mustang?

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    Questions & Answers (41)

    5 Top Rated Questions

    Do you think this cat back would be too loud for someone who lives in an apartment complex and leaves for work at 5 AM?

    • As long as you are not on the gas these would on the mellow side at low RPMs.

    Helpful (1)

    This is a great looking product! Is there any chance MMD will manufacturer a similar line one for the 99-04 mustangs?

    • Hello! Unfortunately, we are not aware that MMD has any plans to produce a similar product for the 99-04 Mustangs.

    Helpful (1)

    Thanks for the 2 reviews, but my question is while she video commentator advises it hangs lower; I have a 1.5 rear drop and 1.5 front drop. It handles well over bumps at 30, 50, or 70 along the highway with 20x9's up front and 20x9.5's in the rear. Dallas Mustang is really the only super mustang shop in Dallas. Not impressed by effort or help to configure a complete exhaust or progess with other mods from them. How much or lower installed than factory exhaust pipes? I can still go over speed bumps, no rub tire or fenders, but it seems this will make my car dent or drag the pipes? By the way the MMD vid explained?

    • Through the use of low profile exhaust tucked up close to the body, the MMD V-Series Side Exit Cat-back Exhaust only lowers ground clearance by approximately 1/2" over a stock exhaust.

    Helpful (1)

    New California law fines vehicles who's exhaust are over 95 decibels when measured 4 inches from the exhaust tip at 3k RPMs in neutral. Do you know what decibels this setup produces under those parameters?

    I understand it doesn't "Fit" the 2018 GT, but is that due to the side skirts, and the dual exhaust cut outs? I have a reputable mechanic telling me, mechanically/structurally underneath the cars are the same as the pre 2018. So would the exhaust part alone, mount up, if i excluded the sideskirts/cut outs.

    Post Your Question
    10 More Questions
    Is this compatible with the gt convertible, if not why? 1 answer
    I have a 2016 gt convertible and assume it would be the premium version? 1 answer
    Can I use an H-pipe instead of the supplied X-pipe? 1 answer
    On the v series side exit exhaust I seen that someone asked if it would fit a v-6 you said question is why? Is it the pipe diameter or something else I looked underneath at a gt and my v-6 and it looks exactly the same Ive been looking to do this on my v6 but can’t find anyone who makes a side outlet for a v-6 so I was going to purchase this but I need to know why won’t it work on the 6 banger Thank you 1 answer
    Has anyone who has had a prior tune on their mustang noticed any loss of power with this exhaust? And if so, is a retune required or suggested? 1 answer
    Is it possible to get the exhaust hole filler plates by themselves? I have this exhaust but the filler plates were not in the package 1 answer
    Is it possible to get the dimensions of the mufflers. I would like to swap them out for the Borla ATAK mufflers. Do you know or carry a set of borla ATAK that would fit this kit, a universal ATAK muffler. Also the MMD vs the 3in Borla ATAK full cat back, Which is louder? 1 answer
    I have a 2017 mustang gt not the premium package tho :(. A guy put aftermarket wheels and borla exhaust on it after he got it so already has a good sound. Is it ok to pair this exhaust with the borla thats on already? And will it void my ford warranty? Lastly any tune required after? 1 answer
    Are there any plans for the 18-19 mustang GT 1 answer
    Will this pass Ga emission? 1 answer

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    Customer Reviews (11) Write a Review

    Overall Rating 3.6

    out of 5 stars

    Installation Time:Afternoon

    Installation Cost:$100-$250

    • Loudness / Volume 4.363636 4.4
    • Exhaust Note 4.636364 4.6
    • Fit & Finish 3.727273 3.7
    • Bang For Your Buck 3.636364 3.6

    • 4/5

      November 19, 2018

      To loud for you?

      I knew from the reviews that these were loud so my solution was to ask a local muffler shop to tie in the factory exhaust, so essentially I have a quad system. Hard to explain the sound but I'll put it this way, a little louder then normal when "driving normal". When you put your foot in it, she comes alive and everyone's head turns. Sounds awesome!!!


      Year: 2017 Submodel: GT

      Helpful (4)

    • 5/5

      Installation Time: Afternoon

      September 10, 2018

      Amazing Sound, Amazing Look

      I couldn't be happier with this exhaust. The sound note is exactly what I was lead to expect from the video, and the look is unrivaled. I turn heads everywhere I go.,


      Year: 2017 Submodel: GT

      Helpful (6)

    • 1/5

      Installation Time: Less than 1 Hour

      February 16, 2018

      Be cautious

      The exaust are wonderful (but) the side skirts are thin and flimsy. They break easy just from driving around the exaust area on both sides. I have asked for a replacement or for a better product from American Muscle. Still have the same broken side skirts.


      Year: 2018 Submodel: GT

      Helpful (12)

    • 4/5

      Installation Time: Afternoon

      June 22, 2017

      Great overall product

      Fitment and finish is dead on. Overall a great sounding exhaust and very unique. I live in alaska and drive the car all year and had no issues with it


      Year: 2015 Submodel: GT

      Helpful (8)

    • 4/5

      Installation Time: Afternoon

      June 22, 2017


      Car had the corsàs, but ive always lliked the Flowmaster, love the muscular sound!


      Year: 2015 Submodel: GT

      Helpful (9)

    • 1/5

      Installation Time: Shop Install

      Installation Cost: $100-$250

      June 13, 2017

      MMD Side Exhaust

      Fit and finish is fair? Side panels do not fit well. This system is way too LOUD. Mufflers in this kit way to loud. I have had side exhaust on my other Mustangs and you could live with the sound. The problem with this system is the Flowmaster mufflers. I HAVE HAD THIS SYSTEM REMOVED FROM MY MUSTANG.


      Year: 2015 Submodel: GT

      Helpful (11)

    • 5/5

      Installation Time: Afternoon

      June 07, 2017

      Now she really sounds like muscle

      Love this exhaust!! Little loud but I did expect that. My neighbors definitely know when I leave in the morning lol!


      Year: 2015 Submodel: GT

      Helpful (9)

    • 3/5

      Installation Time: Less than 1 Hour

      May 04, 2017

      Side exhaust

      If you like annoyingly loud this is for you. I was expecting loud but not wake the dead loud. I uninstalled and sold to someone else.


      Year: 2016 Submodel: GT

      Helpful (9)

    • 5/5

      Installation Time: Afternoon

      April 26, 2017


      So I read the reviews before I bought and I honestly was stuck. One person's didn't fit right and leaked and the other loved it. So I took a Leap of Faith and bought them. The X-Pipes are not stable to my satisfaction, meaning because they don't have a hanger they can bounce causing the mufflers to slide or come off, but surprisingly I haven't had any issue with leaks or really anything really. However, I had an issue with one of the mufflers being a hair too big making it difficult to really tighten them on and the tips block the factory Jacking Port to lift the car. So I'd advise installing some jacking rails first. Sound amazing! Looks amazing. My panels came damaged but I like it better with out them anyway. Sent them back for a partial refund and bought more Mods with the store credit. Very straight forward installation and the second i turned my stang on 3 car alarms around me went off. Epic head turner, unique look, extremely loud in the best way possible and sounds so smooth.


      Year: 2016 Submodel: GT

      Helpful (17)

    • 3/5

      Installation Time: Afternoon

      December 01, 2016

      It's been about 3 weeks... 2.5 stars, really.

      First off, the exhaust adds a completely unique look that pretty much no Mustang in your area will have. And the noise is a great mix of deep bass at low RPM's with that "GT race car" scream at high RPM's. It's not for those seeking subtlety. It will turn heads. That being said, I have not been entirely happy with this system. The fit and finish is lacking as the mufflers and pipes were off by an 1/8" in diameter, easily; making the included clamps kind of a joke in regards towards making exhaust leaks nonexistent. I've had to readjust these sections twice on both pipes in 3 weeks. I'm going to have to get the pipes welded together to keep the leaks from coming back, it seems. The side skirt aspect, is also lacking. It feels a little cheap and is only held on by tape with gaps along the body line, which raises an eye brow towards long-term "worthiness". I decided to leave the skirts off and the car actually looks more aggressive without them, making the exhaust tips stand out more. And no, the tips don't burn you exiting the car or leave any soot on the body. Leaving off the skirts also saves you a little more ground clearance, making the downside of this side-exit exhaust negligible. Given the actually amount of materials and quality of the parts included, this system should be around half the cost with an option for the skirts. There's considerably less metal than a standard-sized system and just tossed-in Flow Master's. However, it is unique and sounds like glorious thunder... when it's not leaking exhaust fumes; the slip-over pipe design needs to be reworked. Parts of me really likes this exhaust, the other half wishes I should have forgone the unique look and just bought something more premium for the cost.


      Year: 2016 Submodel: GT

      Helpful (12)

    • 5/5

      Installation Time: Afternoon

      October 18, 2016

      Turn up the volume!

      I installed my MMD side exit exhaust kit last week and I can't say enough good things about it. Install took less than 2 hours and is as easy to do as any other catback system. The side skirt covers give a super aggressive look, with the square tip pipes just sneaking out of the skirts. It's actually kind of stealthy until you look close or start the car up! The sound is awesome, the flowmaster mufflers provide a deep tone at idle and they scream under wide open throttle. I have mine paired with Pypes catted long tubes and it's extremely loud. If you looking for a mild exhaust, this probably isn't the kit for you. But if you want something that turns heads both with looks and super aggressive sound, you will love this system.


      Year: 2015 Submodel: GT

      Helpful (13)

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