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Flowmaster American Thunder Classic Axle-Back Exhaust (13-14 GT)

AmericanMuscle no longer carries the Flowmaster American Thunder Classic Axle-Back Exhaust (13-14 GT). Please check out 2010-2014 Mustang Axle-Back Exhaust for an updated selection.
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Features, Video & Details

  • Aggressive Flowmaster Super 44 Series Sound
  • Durable 409 Stainless Steel Construction
  • 2.75" Mandel-Bent Tubing
  • 4" Polished Stainless Steel Tips
  • Super 44 Series Mufflers
  • Direct Fit Replacement Upgrade
  • Made in the USA
  • Fits 2013-2014 GT Mustangs

Review & Installation Video

Review & Install Video

Hey, everybody. I'm Justin with americanmuscle.com, and this is my detailed review and install of the MBRP Black Series cat-back exhaust system featuring the dual same side exit configuration which will dump before the passenger side rear tire. It's available for your 2015 and newer 2.7L EcoBoost-powered F-150. My review on this exhaust will cover my thoughts on the overall sound profile you can expect from the MBRP, what the Black Series is going to deliver as far as construction and materials, and then finally we'll briefly talk you through the install, and depending on your cab and bed size, there might be the smallest amount of trimming needed for the lead pipe here. Nevertheless, I'm still going one out of three wrenches on the difficulty meter with some more detail later on. So the Black Series cat-back from MBRP is a pretty unique system in their lineup but the main feature being the black powder coating from tip to tip here, increasing the durability in the process, but also making for a very stealthy appearance underneath the truck. Now this system will produce a good amount of bark overall on your F-150, and it does feature that very cool dual same side exit configuration much like those early SVT Lightnings. Now that you know a little bit more about this system, let's get further into detail. And as I did just mention, this thing does feature that dual same side exit configuration, but we will talk a little bit more about appearance and construction in a little bit. But first, let's dive head first into the sound. And you guys heard the sound clips with this exhaust. You can be the judge, but in my opinion, the MBRP Black Series produces a very well-rounded note overall, and it's a note that we've heard before. It's a tone that we've heard before, because a lot of the MBRP systems, whether it be the Black system that we have here, the XP system, the Installer Series, or the Pro Series, for the most part, are all going to use a very similar design in muffler, so the sound is very consistent across the board. So breaking out the Wake the Neighbors scale, again guys, three out of five on my one to five on the Wake the Neighbors scale. You do hear this thing a little bit more on the inside of the truck, which isn't a huge deal. If you want something that's going to be a little bit more quiet but still deliver that dual same side exit look, check out some of the Magnaflow systems instead. They might be a little bit more quiet on the inside, but you are going to be paying a little bit more for those. However, if you're not bothered by a little added noise inside the truck, this is certainly going to be a great choice. But with the sound covered, let's talk a little bit more about what the Black Series will bring to the table as far as construction and materials. Now, believe it or not, the Black Series actually starts out life as the Installer Series from MBRP, which is the company's most affordable cat-back in their lineup. From there, however, is how the system gets its name. The entire thing, and I'm talking piping, clamps, hangers, tips, muffler, everything gets powder coated in this heat resistant black ceramic coating, giving it a little bit more durability and adding a little bit more of a stealthy look in the process. And this really is going to appeal to truck owners out there from both a function and a form standpoint. Now on the form side, the all-black appearance here really is going to be very unique. There's really nothing quite like it currently in the market that I'm aware of offering that all-black finish. And for those owners out there who prefer to see the system kind of disappear from underneath the truck, this would definitely be a good option. But taking things a step further, let's talk about how that black powder coating will increase the durability of this system and help the function in that regard. And guys, don't forget this thing is the Installer Series, right? It's that aluminized steel tubing lying beneath that black powder coat. The aluminized steel, not a bad material. It's super affordable, it's going to perform as advertised, just as good as any of those other more premium materials.The problem with that aluminized steel, though, is that it can corrode pretty easily, especially if your truck gets exposed to a lot of road salt during the winter months. But the Black Series here with that powder coat is going to act as an additional barrier against the road salt or against the elements, protecting this thing much better than if it were left uncoated altogether. And as such, MBRP is throwing a little better of a warranty at this thing. You're getting a one-year warranty on the coating itself, three-year warranty on the actual materials. You are paying a little bit more for that black powder coat as expected. Mid-$500 price range for this particular system. Definitely not bad and still very much in the entry level category on the site. So now that we've beaten that black powder coat to death, let's talk a little bit more about what you can expect with the MBRP as far as overall construction. Sixteen gauge aluminized steel for the overall material here, 3" tubing pretty much from tip to tip here again including the lead-in pipe going through the straight through by design muffler does split off into twin 3" tubing all mandrel bent before exiting out the 4" slash-cut tips with the rolled edge. These guys are actually made from 304-grade stainless steel, but they are given that same black powder coat treatment as the rest of the system. Let's switch gears quickly and just breeze over the install with the MBRP system. And as I mentioned at the very top of this video, depending on your cabin bed size or basically your wheelbase, you might have to make some small adjustments or some small trimming to this main pipe here. Really, not the end of the world. It's really only going to be one cut. So as long as you take your time, follow the detailed instructions, measure twice and cut once, it's going to be a very easy day in the garage or shop. So I'm sticking to one out of three wrenches on the difficulty meter. Maybe an hour or two before you're making some noise. Obviously, that factory system will need to get dropped first. You can pretty much do this with a basic socket set or an impact gun. After that, simply get to work installing the MBRP in reverse order. I recommend starting from front to back as always. Save your final tighten up to the very end, and you should be good to go. The Black Series from MBRP, while a little pricey compared to some of the other options in their lineup, is going to offer a great sound for your F-150, along with a very unique look, thanks to that all-black powder coat which will also add some durability in the process. So that is my review of the MBRP Black Series which you can find right here at americanmuscle.com.

Classic Flowmaster Sound. Give your 2013-2014 GT that unmistakeable Flowmaster sound with a nice power boost with the American Thunder Axle-Back exhaust system. This system improves exhaust flow using Flowmaster's patented chambered muffler design for that throaty, aggressive exhaust tone your high powered Pony deserves.

Quality Construction. Constructed from durable 3" 409 stainless steel tubing for its resistance to corrosion, the Flowmaster Axle-Back features (2) special 5" X 10" chambered Super 44 Series Flowmaster mufflers with 4" diameter polished stainless steel tips for muscle car looks and sound. As an added bonus, the tip is embossed with the "Flowmaster" logo for true custom styling.

Direct Fit Upgrade. This Flowmaster American Thunder Classic Axle-Back Exhaust includes all the hangers and clamps needed to bolt up in the stock location without any modifications required, making it a direct fit replacement upgrade.

Application. This Flowmaster American Thunder Axle-Back Exhaust System is designed to fit the 2013-2014 GT models equipped with the Coyote 5.0L 4V V8 engine.

Fitment: 2013 2014 Details

MPN# 817588

CA Residents: WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov

What's in the Box
  • (2) Mufflers
  • (2) 3/8" Hanger Keepers
Installation Info
Tech Specs
Axle-Back Exhaust Specifications
Piping Material: 409 Stainless Steel Tip Material : Polished Stainless Steel
Piping Size: 3" Tip Size: 4"
Muffler Type: Chambered Fitment: 2013-2014 GT 
Will it fit my Mustang?

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Questions & Answers (9)

5 Top Rated Questions

Will it fit a 2014 v6 mustang ?

  • No, the Flowmaster American Thunder Classic Axle-Back Exhaust is designed to only fit the '13-'14 GT primarily due to the inlet pipe diameter.

Helpful (1)

Hello..this fit for Mustang gt Premium pakege 2014 thank you.

  • Yes, this exhaust will fit a 2014 Mustang GT Premium.

Helpful (0)

will this fit a 2014 ford mustang v6 if so how will it sound.

  • Unfortunately, this is not designed to work with a 2014 V6 mustang, they are meant for the 2013-2014 mustang GT models, we do carry a similar axleback exhaust that is slightly louder than this is that would work for the V6, the flowmaster force II axleback item 18414. https://www.americanmuscle.com/flowmaster-forceii-axleback-2011v6.html

Helpful (0)

I bought a pair of these a few months ago and I love their sound but the Drone is horrible from 1700rpm to 2200rpm. Is there anything that I can do to reduce the Drone?

  • To reduce the drone, additional mufflers could be added to the exhaust system. Additionally, the installation of Boom Mats, would help reduce in-cabin noise.

Helpful (0)

will these void factory warranty?

  • Not at all put them on and it will sound good

Helpful (0)
Post Your Question
4 More Questions
I currently have the Outlaw series on my 13 GT...... I do love the aggressive sound but it is a daily driver and the cabin noise and drone is a little too much for me, ( I bought the car with these already installed) Does this series tone it down or does someone have recommendations for a different axel back ? 2 answers
Is there a difference in axle backs from 2011-2012 to 2013-2014? I would like to run the Super 44 Series mufflers, listed here fitting 2013-2014 GT models. Will these fit on a 2012 GT? 1 answer
I'm wondering if the American thunder is the 60 delta flow muffler or the 44 series? In the video for the force 2 Justin says that the American thunder is the 60 series. I want the 60 series not sure which one to purchase. Thank you 1 answer
Do you need a tune after install? 3 answers

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Customer Reviews (87) Write a Review

Overall Rating 4.6

out of 5 stars

Installation Time:Afternoon

Installation Cost:0-$100

  • Loudness / Volume 4.529412 4.5
  • Exhaust Note 4.647059 4.6
  • Fit & Finish 4.8 4.8
  • Bang For Your Buck 4.564706 4.6



  • 5/5

    Installation Time: Less than 1 Hour

    January 09, 2019

    Awesome! Sound

    Sounds Great, not too loud and very nice deep sound.

    FHufty

    Year: 2014 Submodel: GT

    Helpful (4)

  • 4/5

    December 19, 2018

    Roaring Thunder

    Easy installation. After driving a few times, sound improves to a nice roar.

    KarenH

    Year: 2014 Submodel: GT

    Helpful (4)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: $100-$250

    July 27, 2018

    THE ROAR

    Im so glad i purchased the flowmaster , AT Classic ! This Exhaust made me more than happy. Its the perfect roar for my 5.0 and i love that it makes just enough noise to let people know Im coming but doesnt wake the neighbors . THe coldstart is the Best. Loud Rumble early in the Am but doesnt drown out your music. WOuld highly recommend

    Sassy70

    Year: 2014 Submodel: GT

    Helpful (5)

  • 3/5

    Installation Time: Less than 1 Hour

    May 03, 2018

    Blegh...

    Sounds good if these are one of your only exhaust upgrades, but if you’re fully upgraded LTH and everything down to the mufflers! Then walk away from these now! Drone almost throughout the entire rpm range and ridiculously loud when pair with entire exhaust upgrades. TOO MUCH! Save ur money bro/chica and look elsewhere.

    Mamba

    Year: 2013 Submodel: GT

    Helpful (6)

  • 1/5

    February 21, 2018

    Noise and drone

    The sound is noisy. From outside the car and from inside

    MOHAMEDA

    Year: 2013 Submodel: GT

    Helpful (6)

  • 5/5

    Installation Time: Less than 1 Hour

    January 04, 2018

    Exhaust Upgrade

    Nice aggressive sound. Interior is a little loud. I get compliments all the time on the sound of my car.

    SamC

    Year: 2014 Submodel: GT

    Helpful (6)

  • 4/5

    Installation Time: Afternoon

    December 29, 2017

    Good sound

    I really like these mufflers got a good throaty sound. That being said does have a bit of a dron at 2k rpms

    TrevorH

    Year: 2014 Submodel: GT

    Helpful (6)

  • 5/5

    Installation Time: Less than 1 Hour

    September 06, 2017

    Great sound, minimal drone.

    Had Pype Bombs, they were too loud. These give you the best of both worlds. Nice deep trouble, minimal in cabin drone.

    MarkZ

    Year: 2014 Submodel: GT

    Helpful (6)

  • 5/5

    Installation Time: Less than 1 Hour

    June 30, 2017

    Love them

    Had a slight droning between first and second gear when not getting on it but after about a month it seems to have gone away or I just don't notice, definitely made the right decision after weeks of watching videos of all types and brands and I feel I couldn't have made a better choice. Would definitely recommend if you're looking for a deep throaty muscle car rumble.

    DanielA

    Year: 2013 Submodel: GT

    Helpful (7)

  • 5/5

    Installation Time: Less than 1 Hour

    April 27, 2017

    Sound

    The new muffler sounds great on my car!!!!A great product, I good your product.

    EricG

    Year: 2013 Submodel: GT

    Helpful (6)

  • 1/5

    Installation Time: Less than 1 Hour

    April 10, 2017

    Very disappointed

    While the Flowmaster American Thunder exhaust was very easy to install on my 2013 Mustang GT, and are well made, the loudness rating is not at all accurate. The loud and constant drone at 2000 rpm while at cruising speed is oppressive and the roar and vibration in car when accelerating while cruising is annoyingly loud. I had the flowmaster exhaust system on my previous 2006 Mustang GT and they were loud and had great exhaust note at lower speeds and rpm, but did not have an oppressive drone at cruising speed. I will be taking the mufflers off and selling them on ebay and save up for a set of Borlas. I suggest the loudness information be corrected so others don't make the costly mistake I made.

    JohnL

    Year: 2013 Submodel: GT

    Helpful (8)

  • 5/5

    Installation Time: Less than 1 Hour

    March 02, 2017

    Nice axle-back exhaust

    Very nice and not too loud not too quiet very easy to install has a nice little Rumble to it

    BigSam812

    Year: 2013 Submodel: GT

    Helpful (7)

  • 5/5

    Installation Time: Afternoon

    January 19, 2017

    Great sound!

    This is the sound a 2014 Mustang GT should make. , I would suggest actually removing the brackets that hold the rubber isolators you can get a wrench and sockets on all the bolts. Makes the install much easier. You will get some drone at 2000 rpm but it's not terrible.

    Jamiep

    Year: 2014 Submodel: GT

    Helpful (7)

  • 5/5

    Installation Time: Afternoon

    December 30, 2016

    Martin Mustang/Flowmaters

    Sounds good cruising down the road not to loud, when you give it the gas you can really hear the performance of that coyote motor and turn some heads.

    MartinMustang

    Year: 2014 Submodel: GT

    Helpful (7)

  • 5/5

    Installation Time: Afternoon

    December 16, 2016

    excellent product

    easy to install quality of exhaust excellent sound is what i wanted

    jock

    Year: 2014 Submodel: GT500

    Helpful (6)

  • 4/5

    July 27, 2016

    Great Sound

    I love the sound. I have a convertible and at first it was too loud, but a week later it doesn't seem as loud. There is more drone than I thought there would be. Overall I'm very satisfied with this product.

    Lj

    Year: 2014 Submodel: GT

    Helpful (8)

  • 1/5

    July 21, 2016

    Horrible Drone

    Buy the Roush or call me and you can have myour Flowmaster. I don't want them.

    KungFuCooter

    Year: 2014 Submodel: GT

    Helpful (6)

  • 3/5

    Installation Time: Afternoon

    June 18, 2016

    Wish that I could rate it higher on its loudness.

    First of all it took over a hour for the left side but after lessons learned and wrestling the other stock muffler out I popped the right side in around 5 minutes later. As far as the sound, it's sounds great. My buddy has Roush and I didn't want the same even though his sounds great. So watching the American Muscle video I thought these would be just a little lower tone. WRONG ! These are Freaking Loud ! It has a lot of drone and on the interstate I want to put in ear plugs. If you have a good looking girlfriend that only talks about stupid stuff that you don't want to hear about get these. If you have a toddler in the back seat that you want to talk to, well keep looking. I wish that I could send them back and get something at a lower level. But it turns heads everytime I crank it up. Now I don't know if I will put headers on or not. Don't think that I can drive it if it gets any louder.

    KungFuCooter

    Year: 2014 Submodel: GT

    Helpful (5)

  • 5/5

    June 06, 2016

    Great deep tone.

    Installed American thunder axelback first by itself and it provided a nice deep burbly exhaust tone that was nice but not aggressive enough for me. Then installed an X-pipe along with a Resonator delete...Very deep and aggressive sound with normal driving but once you put the pedal to the floor its just an angry dragon mating call!Axelback by itself really not any noticeable drone but if you do Resonator delete you will have some on the highway so beware.

    BryanB

    Year: 2014 Submodel: GT

    Helpful (6)

  • 5/5

    Installation Time: Less than 1 Hour

    May 30, 2016

    Now it sounds like a mustang.

    Before it sounded like a family car, now it sounds like a muscle car. They look much better from the back, nothing hanging down, flush fit. Less than a hour to install. Turned my pony into a stallion. I love the deep thunder sound it makes at certain times. This to me is the best flowmaster made.

    rickdavis

    Year: 2014 Submodel: GT

    Helpful (5)

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