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SLP Loudmouth Axle-Back Exhaust (11-14 GT; 11-12 GT500)

Market Price $439.95 You Save 4% ($17.00)
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  • Item 23042
  • MPN# M31023

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    Features, Video & Details

    • Rich, Throaty Exhaust Sound
    • Muffler Delete
    • 2.5" Mandrel-Bent 409 Stainless Steel Tubing
    • 4" Polished 304 Stainless Steel Tips
    • Emissions Legal in All 50 States
    • Fits 2011-2014 GT and GT500 Mustangs

    Review & Installation Video

    Review & Install Video

    Hey what’s up everyone I’m Justin from, and I’m bringing you SLP’s loudmouth axle-back exhaust, for your 2011 and up GT Mustang. This loudmouth system eliminates the restrictive factory mufflers, which allows for more horsepower, it also makes for one mean exhaust note as well. The system is constructed from 3 inch mandrel bent stainless steel tubing, exiting through hand polished 4 inch tips, which result in a very clean finish. Simple bolt on installation, should only take you about an hour. Let’s hear how SLP’s loudmouth axle-back compares to your factory exhaust.

    Aggressive Throaty Exhaust Note. This SLP Performance Parts Axle-Back kit eliminates the restrictive stock mufflers from the 2011-2014 GT or GT500, drastically reducing back pressure to enhance power and to produce one of the most aggressive exhaust notes possible with the factory catalytic converters still installed.

    409 Stainless Steel. SLP's Loud Mouth axle-back system is made from 2.5" mandrel-bent 409 stainless steel tubing, which has excellent flow characteristics and features pre-welded hangers for simple installation. The hand polished, 4" dual wall tips give a show quality muscle car appearance to the rear of your Pony.

    Application. Made as a direct bolt on, this SLP Loudmouth Axle-Back bolts right up in the stock location without any modifications required on the 2011-2014 GT or GT500 Mustangs.

    Technical Note: Americanmuscle recommends adding the 2005+ Mustang 304 Stainless Steel Exhaust Hanger Kit from the drop down option above, to provide more strength, stability and a cleaner installed appearance. If you have a 2007 Mustang you may need the kit for correct installation.

    Fitment: 2011 2012 2013 2014 Details

    What's in the Box
    Hardware included: Hardware Included
    • (2) Clamps
    Installation Info
    Tech Specs
    Axle-Back Exhaust Specifications
    Piping Material: 409 Stainless Steel Tip Material : Polished 304 Stainless Steel
    Piping Size: 2.5" Tip Size: 4"
    Muffler Type: None Fitment: 2011-2014 GT and GT500 Mustangs
    Will it fit my Mustang?
    • Boss 302 - 12, 13
    • GT - 11, 12, 13, 14
    • GT500 - 11, 12, 13, 14

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    12 Questions / 6 Answers

    Ask a Question

    Will this work with the LTH Over Axle Pipes (11-14 GT, GT500)?


    • The LTH over axle pipes have a diameter of 2.75" whereas the SLP Loudmouth axleback exhaust has a 3" pipe diameter. For these to work together you will need a 2.75" to 3" step up pipe modified for proper installation.


    Helpful (0)

    Debating on these or flowmaster outlaw for my GT500 is their any back pressure in these or the flowmaster outlaws??


    • There will not be any back pressure with these SLP Loudmouth's or with the Flowmaster Outlaws if they have been installed correctly.


    Helpful (0)

    I have these and they drone way too much around 1.7k-3k, I heard I can buy a mid pipe and fix this issue. Can you guys recommend one for this problem


    • Hello! We have many different options to take when looking at mid pipes, I would recommend that you look at one that is catted, if you are looking to quiet down the drone a little bit!

      Doug P

    Helpful (0)

    I'm stuck between getting the SLP or Flowmaster Outlaws. I want the one that has a real good tone to it and sounds like thunder clapping. is muffler deletion better? I'm leaning more towards the SLP but I need some help.


    • What up I actually have the outlaws when i first had jus axleback the tone was great it was loud enough that u could be heard but not to much that its over baring but now i am full off road x pipes with cat deletes and lets jus say i have to stop driving to talk on the phone and i heard these slp in person im 25 im still young and i love the loud and wanna be louder but if u want to go over the top with loud go with the slp i warn u doe if u plan on goin cat less with a x/h pipe be ready to make ur neighbors mad


    Helpful (0)

    Are the tips interchangeable. I want black tips and other than having them powder coated can these be changed out with black tips or no?


    • You can change the tips since they are clamped on. As long as the ones you are going for are the same size, then you should not have any problems.


    Helpful (0)

    I got a 14 shelby and ordered the loudmouths, do I have to have the exhaust hanger kit or is it optional?


    • With the SLP Loudmouth Axle-Back Exhaust (11-14 GT & GT500), you will not need to purchase the SR Performance Stainless Steel Exhaust Hanger Kit (05-10 All) item #20021 ( however I recommend it for more strength and stability.


    Helpful (0)

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    Customer Reviews (81) Write a Review

    Overall Rating 4.6

    out of 5 stars

    Installation Time:Afternoon

    Installation Cost:0-$100

    • Loudness / Volume 4.791045 4.8
    • Exhaust Note 4.712121 4.7
    • Fit & Finish 4.447761 4.4
    • Bang For Your Buck 4.417911 4.4

    • 5/5

      April 09, 2011


      HOLY CRAP is all I have to say!!! I've owned 2 mustangs and the other one had the pype violaters on my 2010 4.6L, Now I have a 5.0 with these SLP's and OMG!!! Night and DAY DIFFERENCE. I've had 4 people ask me if I took the cat's off or put headers on. When I told them nope its just axle-backs, they said HAHA Yah right... Haha!! WOOH This is the best sound upgrade for this car for the price FIVE STAR!


      Year: 2011 Submodel: GT

      Helpful (11)

    • 5/5

      December 14, 2010

      Simply Outstanding

      After the first 30 minutes of having it installed, I was complimented by 3 random people. It is a very noticeable difference from the stock exhaust. I love the sound of it when you get on it. Very loud and will surely turn heads.

      Brett H.

      Helpful (10)

    • 1/5

      Installation Time: Afternoon

      December 11, 2012

      Sounds great, fit is lacking

      Sounds awesome, had these as well on my 2009 GT/ Was extremely excitied to install, only to see they do not fit very nicely on a 2013.....they dont sit flush or centered in the openings, I messed with it trying to get it to fit better, but the way the hangers are on make it impossible to re-arrange. Sounds good, but if you care about your car's looks I'd go with something else. These will be gone as soon as I can afford a different set.


      Year: 2013 Submodel: GT Los Angeles

      Helpful (6)

      • Response from AmericanMuscle

        I'd suggest taking this to a shop to find out if they are actually defective or if they can be bent a bit to fit better. I haven't heard of this issue previously and I'd like to be able to send you a replacement that fits as it should after we figure out the cause. Please give us a call so that we help you get this resolved!

        Lisa, Customer Care

    • 5/5

      Installation Time: Shop Install

      March 04, 2012

      Get This

      Very Aggressive Note but sounds great. I got this for my 2012 GT the week after getting my car. Soooo glad I did. I had a guy in a GT500 track me down and pull me over after passing him at an intersection. He wanted to know what exhaust I had so he could get the same and was surprised it was just an axleback.


      Year: 2012 Submodel: GT Tampa, FL

      Helpful (5)

    • 5/5

      Installation Time: Less than 1 Hour

      January 27, 2012

      Awsome Sounding

      2011 5.0, Manual, 3.73's. It took me and friend about 1 hour to unbolt factory mufflers and install SLP's. SLP's fit right up and positioning them was no problem. Tips look huge compared to stock. Fired the car up, 3 neighbors came out to see what the noise was. The SLP's are LOUD and THROATY, just the sound I wanted. Sound at cruise is moderate, there is drone at 65mph in 6th, goes away at 70 mph, WOT is SICK!!!! There is no video clip that you can listen to that does these things justice. Highly Recommend.


      Year: 2011 Submodel: GT Gilbert, AZ

      Helpful (5)

    • 5/5

      Installation Time: Less than 1 Hour

      June 08, 2014

      great choice

      I upgraded from an 07 gt to a 14 gt. I had an off road x pipe and flowmasters on my 07. it was loud! with my 14 I decided I was going to keep the cats on this time. this led me to research more aggressive axle backs. I went with the slp loudmouth because of the aggressiveness of the muffler delete. I chose the slp over magnaflow because they seemed to be of equal quality but slp was better on my wallet. I didn't want to waste my money on the heartthrob exhaust with the cheap materials it included. the slp fit perfect and looks great. the sound is amazing. somewhat calm at idle but starts to really growl at the slightest touch of the throttle and screams when its wide open. very happy with my purchase. If you want loud but want to stay street legal this is for you. Btw my buddy got the pypebomb and mine is def louder< especially when you get on it


      Year: 2014 Submodel: GT Texas, USA

      Helpful (4)

    • 5/5

      Installation Time: Afternoon

      September 26, 2011


      Took off the Stock 2012 GT/CS exhaust and What A Difference!!! My wife hates them, my son and friends love them!! :) SLP Loudmouth axlebacks are incredible, and I'm getting 2 extra MPG!!! Sounds fantastic, and looks awesome...I put the tips quite a bit further Aft and now it looks and sounds the way a mustang should.


      Year: 2012 Submodel: GT Sumter SC

      Helpful (3)

    • 5/5

      June 21, 2011

      Slp loudmouth

      Just put in on my 2012 mustang, and there is only two words to describe it, Freaking Awsome! Best exhaust i've ever had!

      Justin G

      Year: 2012 Submodel: GT

      Helpful (3)

    • 5/5

      May 24, 2011

      SLP Loudmouth

      Easy install. Didnt even lift the car. Stock mufflers a little tough but I was on my back and the car was not lifted at all. Huge sound difference!! If you want loud, buy this exhaust. Hope to add BBK long tubes and off road X next.


      Year: 2011 Submodel: GT

      Helpful (3)

    • 5/5

      February 08, 2011

      Slp 2011

      The product was simple to install took me 25 minutes. Works wonders for the 2011 best bang for the buck

      Ashton Slaughter

      Year: 2011

      Helpful (3)

    • 5/5

      Installation Time: Less than 1 Hour

      January 14, 2016

      sounds like thunder- the best!

      the install was an easy drop in and "bolt on" took about 40 mins to do - it was fairly straight forward and honestly you cant get a better sound from any other axle back than this one. NO raspy kick back - drone is only present during RPM build up (2200 rpms or so) in 6th gear its super quiet. Id suggest NOT cutting off teh resonators. It doesnt add any more hp or TQ and it will cause ALOT of drone and vibration if you do.


      Year: 2014 Submodel: GT Stockton, CA

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      April 16, 2013

      Pure wow!

      I just installed these today on my 2011 5.0 and man did my car come to life! For those of you who are looking for a mellow exhaust, walk away now! These bad boys are LOUD! Nice and loud startup/warm up, really nice and deep "burble" on idle that gives the car an "I'm ready and waiting" attitude at a volume that is not too loud but rather just perfect, and an absolutely STUNNING and just pure raw wide-open throttle sound. Definitely a must-have for those of you who are looking for a pure, raw sound. Mustangs have always had a unique sound as opposed to other V8's in its class. With an SLP Loudmouth axle-back exhaust system, you can make sure they know what you have and they will never forget the sound.


      Year: 2011 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Afternoon

      January 12, 2013

      Great sound - Lots of compliments

      Been running these for 8,000 miles, and couldn't be happier. I commute 30 freeway miles each way - they're loud, there's some drone and I knew that going in. Probably should take it easy around cops, although all the cops I know love the sound. It's an aggressive sound, not for softies or those living in HOA areas, but it's my opinion that the Coyote should sound this way from the factory. Install is as painless as could be, but I had to cut a notch in the hanger bracket because the hanger arm rattled against it. They also sound great with straight cat to axel pipes.


      Year: 2013 Submodel: GT LA, CA

      Helpful (2)

    • 3/5

      Installation Time: Shop Install

      Installation Cost: 0-$100

      December 03, 2012

      Too much drone

      If you drive at or around 1.7-3k rpm this thing drones way too much. Wish I would have bought a different one. I also set off car alarms when i start my car


      Year: 2013 Submodel: GT Houston, TX, USA

      Helpful (2)

      • Response from AmericanMuscle

        Many people have had success eliminating some exhaust drone by adding an aftermarket mid-pipe to the set up. If you'd like any suggestions on which mid-pipe would be best for you, definitely give us call - we'd be happy to help!

        Lisa, Customer Care

    • 5/5

      Installation Time: Less than 1 Hour

      March 06, 2012

      Sounds good.

      I was worried about having it being raspy but it wasn't at all. This is how is should have came from the factory. Sounds good!!! Hardest part of install is removing the stock mufflers, after that it's cake. If you decide to go with an off road H-Pipe I recommend leaving the factory resonators on. True Story.


      Year: 2012 Submodel: GT Dallas

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      March 01, 2017

      Awesome sounding exhaust!!

      I love the way it rumbles! Now all my 5.0 needs is some longtubes to be louder!


      Year: 2014 Submodel: GT

      Helpful (1)

    • 5/5

      Installation Time: Shop Install

      Installation Cost: 0-$100

      February 21, 2016

      Everything I hoped it would be

      I'm never satisfied with a stock exhaust, even though the Shelby has a great exhaust note from the factory. Basically I was looking to keep the rumble and pop of the stock exhaust and just knock it all up a few decibels, and that's exactly what the SLP Loudmouth did for me. A local shop did the install in about an hour and everything fit with no issues. The longest time was removing the original mufflers. On the initial fire up, I knew I made the right choice. It really comes alive after 3K on the tach, and it's very attention getting. Since mine is a convertible, I get an even better dose of the exhaust note behind my ear, so I can truly say that with the stock exhaust I didn't always hear it, but now it is always audible. This is a cost effective solution for getting more attention. I had numerous people on the very first day making head turns and making compliments. Highly recommended! Thanks again to AM!


      Year: 2011 Submodel: GT500 Columbus, GA

      Helpful (1)

    • 5/5

      Installation Time: Less than 1 Hour

      April 04, 2015

      This Exhaust DELIVERS!

      Having been a 4-time Mustang owner, trying to decide what exhaust to go with can be tedious. YouTube video, after YouTube video, etc. I was surprised that there weren't too many Coyotes running the SLP Loudmouth. I'm so glad I took a chance and got these. I work at a Ford Dealer and I hear so many Coyotes with the Roush Axlebacks. This has the same aggressive tone, slightly louder....but with less rasp!! Only had to drive the car for ONE day for it to smooth out. No drone at idle, minimal drone at highway speed, and it took less than an hour to install. Fast shipping as usual. Great job AM! Keep it up!


      Year: 2011 Submodel: GT Addison, TX

      Helpful (1)

    • 5/5

      September 11, 2014

      You will not believe the difference

      I have a 2012 Shelby, I liked the stock exhaust sound, but I wanted more. I installed these pipes and it is a different car. it is THE BEAST! You can now hear every bit of the 600+ horsepower. Warning: It take a lot of finesse to not make a lot of noise, but when you open it up, the volume, depth, and voracity of the exhaust is nothing short of amazing. It there is an exhaust that is louder, I cannot imagine it. The car now sounds like it eats small children and pets. The exhaust was the only thing I changed. I would not have believed the difference. This is what a V8 muscle car should sound like..


      Year: 2012 Submodel: Cobra Virginia

      Helpful (1)

    • 5/5

      Installation Time: Shop Install

      Installation Cost: 0-$100

      April 29, 2014

      No one believe's it's only an axle back

      Slp loudmouths are LOUD. Had them shop installed because I couldn't get the car high enough. Took them about 1 hour to do in total. As for the exhaust, they're perfect. I love the tone and when your just cruising they aren't bad at all and then on WOT they open right up and everyone around is looking. Since I've put them on the infamous line I've gotten "I heard ya before I saw ya." And I'm talking way before they saw me. The tips look great too, the guy at the shop had pulled em out a little so you can see the SLP on the tip and they look aggressive now compared to the ugly stock tips. Overall great bang for your buck


      Year: 2014 Submodel: GT

      Helpful (1)

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