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SLP Loudmouth II Axle-back Exhaust (15-17 GT Fastback)

Market Price $499.95 You Save 10% ($51.00)
Our Price

$448.95 (pair)

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  • Item 387059
  • MPN# 620055

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Features, Video & Details

  • Sporty Muscle Car Sound
  • Durable 409 Stainless Steel Construction
  • 2.5" Mandrel-Bent Tubing
  • 4" Polished 304 Stainless Steel Tips
  • Cut & Clamp Installation
  • Emissions Legal in All 50 States
  • Fits 2015-2017 GT Fastback Mustangs

Review & Installation Video

Review & Install Video

Hey, guys, Stephanie with AmericanMuscle.com here with my review of the SLP Loudmouth II Axle-back Exhaust for 2015 to '16 Fastback GTs. My first impression of this axle-back is that it offers a deeper, more reserved muscle car sound. Around 2,000 to 4,000 rpm, the system does get louder, and it increases in sound as you get into those higher rpms, but it maintains the deepness and throaty quality. It doesn't get raspy at all. Even from inside the car, the axle-back sounds deep and has no drone, which is perfect for a nice cruise or good sound quality from light to light in town. And, luckily, the sound can be there when you want it to be, you've just got to step on it a little bit harder. Keep in mind that this is an axle-back, so you'll be keeping all of your cats and your stock resonator. Now, down the road, you can always change out your resonator for another mid-pipe option and enhance the sound of the axle-back even more, and that's one of the nice things about an axle-back. It offers room to grow and change for different things like mid-pipes, off-road setups, or headers. I'm going to rate it as a two on the loudness scale because while it is deep, it's not the loudest thing out there on the axle-back market. If you're looking for loud from an axle-back, there are other systems out there that are sure to give you what you're looking for. In fact, SLP does have a muffler delete option for you guys out there that are looking for loud. So, we're looking at 2 ½" manual-bent stainless steel tubing with 4" polished stainless steel tips, rocking the SLP name here, and a pair of straight-through mufflers at one of the most budget-friendly prices that we're seeing out there on the market for the S550 GT and from a brand that's known for their exhaust products. I'd say that this is a good deal here if you're looking for a louder but more tame muscle car sound from an axle-back. Install-wise, if you don't know by now, if you're installing an axle-back, you're going to be doing some cutting, and this axle-back is no different. It's a standard cut-and-clamp design that we're used to seeing with other axle-backs, and for that reason, I'm going to stick with what I said in the past and call this a two out of three wrenches on the scale. Time-wise, it's not really going to take too long to install, probably about an hour or so, but you do have to be careful when you're cutting. And remember that this system is not compatible with convertibles. I still just recommend a fresh sawzall blade and some eye protection, just to make sure everything goes smoothly. Wrapping this up, the SLP is one of the inexpensive options on the axle-back scale when we compare it to the rest of the market, and if you're looking for a deep and throaty but more civilized exhaust tone, then this would be a good option for you. The straight-through mufflers are going to wake your 'Stang up some and provide you with a little extra sound and the option to further change your exhaust down the road. As always, feel free to check out the full line-up of axle-back options, here at AmericanMuscle.com.

Sporty Muscle Car Sound. Give your Coyote powered S550 Fastback Mustang a sporty muscle car tone with only minimal harshness by installing a SLP Loudmouth II axle-back exhaust system from AmericanMuscle. The Loudmouth II not only enhances the sound of your late model Mustang, but it also enhances performance by drastically reducing back pressure for an increase in horsepower and torque.

Stainless Steel Construction. Manufactured from 2.5" diameter mandrel-bent stainless steel tubing for its excellent flow characteristics, this SLP Loud Mouth II exhaust system features a pair of straight-through performance mufflers that end with highly polished 4" dual wall exhaust tips for intimidating muscle car looks and sound.

Cut & Clamp Installation. The installation of this Axle-Back Exhaust requires cutting and removing the factory muffler assemblies, and clamping the new muffler assemblies in place. Clamps and instructions are provided.

Application. This SLP Loudmouth II Axle-Back Exhaust system is specifically designed to fit 2015-2017 GT Fastback Mustangs only. Cutting of factory exhaust is required for installation. Not compatible with convertibles.

Fitment: 2015 2016 2017 Details

What's in the Box
  • (2) Axle-Back Assemblies
  • (2) Polished Tips
  • (4) Clamps
Installation Info
Tech Specs
Piping Material: Stainless Steel Tip Material : Polished 304 Stainless Steel
Piping Size: 2.5" Tip Size: 4"
Muffler Type: Straight-through Fitment: 2015-2017 GT Fastback
Will it fit my Mustang?
  • GT - 15, 16, 17

Not compatible with Convertibles due to different bracing

Most Helpful Reviews

5/5
What a difefrence!

I was not disappointed by the end result. Well worth the expense. Sound evil despite the factory resonator still in place. My Shaker sound system is never turned on since my GT has its own soundtrack!

Helpful (1)

5/5
Excellent sound

The SLP LM 2 fit perfectly and the sound is just what I was looking for. Nice deep tone and not obnoxiuos.

Helpful (1)

Overall Rating 4.9 out of 5 stars
Read All 14 Reviews

Customer Photos (9) Submit Your Photo

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2 Questions / 1 Answers

Ask a Question

I have a axle delete kit on and I had to cut my exhaust to get the axle delete on will it fit on my car where I cut my exhaust already??

Prorider246

After the install,will I have the check engine light come on? Sense there's change in torque and back pressure.(2016 gt).thank you.

Pete

  • With the install of the SLP Loudmouth II Axle-back Exhaust - Fastback (15-17 GT) you will not get a check engine light. These will install with no issues.

    Ricky36

Helpful (0)

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Customer Reviews (14) Write a Review

Overall Rating 4.9

out of 5 stars

Installation Time:Less than 1 Hour

  • Loudness / Volume 3.538461 3.5
  • Exhaust Note 4.923077 4.9
  • Fit & Finish 4.923077 4.9
  • Bang For Your Buck 5 5



  • 5/5

    Installation Time: Less than 1 Hour

    May 06, 2017

    What a difefrence!

    I was not disappointed by the end result. Well worth the expense. Sound evil despite the factory resonator still in place. My Shaker sound system is never turned on since my GT has its own soundtrack!

    AnsarM

    Year: 2017 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    December 09, 2016

    Excellent sound

    The SLP LM 2 fit perfectly and the sound is just what I was looking for. Nice deep tone and not obnoxiuos.

    Slink

    Year: 2016 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    December 09, 2016

    slp loudmouth II

    Im happy with the exhaust eveything bolted up easily. Not a loud muffler setup but thats what I wanted great tone and you can hear it. I think these will be perfect with longtubes and a offroad midpipe. They are about as loud as the very popular 11-12 gt500 mufflers.

    jdg

    Year: 2017 Submodel: GT

    Helpful (1)

  • 4/5

    September 04, 2016

    Volume or power?

    Both volume and power much improved; quality decibels to boot. I added this axle back on top of Steeda Pro-flow with restrictor (no tune CAI), x-pipe and Ford Performance Power Pack 1 tune. The straight through axle back bumped the power with the existing mods so much...I can't get enough traction on the street in first or second. Talk about sounding good...guy in a challenger rolled by me at a light yesterday and yelled "Sounds really good!" With just the x-pipe no one noticed the V8 in the lane next to them, not anymore! There is a slight drone at low RPM, less than 2K, but nothing too obtrusive; not overly loud so as to attract the attention of law enforcement. All said and done, I only wish I had put them on sooner. Now for a set of rims and tires in a search for more traction!

    anadventurer1

    Year: 2015 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    June 09, 2016

    Great sound

    So after watching many videos online, I felt this was right for me. It is so hard to tell online and this one sounded a little quiet based on the video. I just want to say that if you want deep muscle car rumble and sound, buy it. It has the same tone as stock, but amplifies the volume by 30-40. Great rumble on startup, mellows out at idle and puts a smile on your face under acceleration. I am not a fan of the raspy exhausts which is why I avoided Corsa and the like. This keeps that stock rumble but turns it up to 11!

    rffanat1c

    Year: 2015 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    March 11, 2016

    Great product

    This product is great! Fitment is perfect, installs in 30 mins- 1 hour. The sound is very deep no rasp or drone what so ever. It is not the loudest exhaust but provides some sound. I would say it's a little louder than stock. When driving around it can be heard inside the car but it is no where close to being bothersome. Over all this product was a great buy!

    5ohsnow

    Year: 2016 Submodel: GT

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    March 11, 2016

    Great axle back for the money!

    I couldn't be happier that I picked this axle back over others. Nice deep rumble. I also paired it with the the heart throb h pipe and it's even better. Cold starts aren't that bad I don't experience any drone but I want say there's no interior noise at all its the noise you want to hear. If you're someone who may think the roush is to loud this is the exhaust for you virtually the same just more packing. I have a video up on you tube. Just search slp loudmouth 2 with h pipe.

    Hinds15

    Year: 2016 Submodel: GT

    Helpful (1)

  • 4/5

    Installation Time: Less than 1 Hour

    September 10, 2015

    Deep muscle sound

    The SLP axle back system is one I would recommend to people who want a nice deep tone, throaty full throttle, but still civilized exhaust. The exhaust itself is not as loud as other axle back systems ive head. If you're after just pure loudness you may consider the muffler delete variant. Overall I still feel this system gives that true muscle car sound, unlike alot of modern axle backs which sound like ricers with v8s. I have some sound clips on youtube @ fivepointoh.

    kez

    Year: 2015 Submodel: GT fort worth, TX

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    August 03, 2017

    perfect sound and volume

    I will admit i was nervous buying this set up because we all know the traditional slp loud as heck raspy tone. However after several videos later i decided to but it anyway. I love this kit! this paired with my ford racing xpipe produces a fantastic tone and volume level. I dont regret this buy in the least and neither will you.

    csn95

    Year: 2017 Submodel: GT

    Helpful (0)

  • 5/5

    Installation Time: Less than 1 Hour

    May 10, 2017

    Great buy

    Installed these a couple days ago and this is how a muscle car is suppose to sound. Paired this with Ford racing x pipe and it's a little louder then expected but no regrets what so ever. Great buy

    BT

    Year: 2017 Submodel: GT

    Helpful (0)

  • 5/5

    December 10, 2016

    All of the sound none of the pop

    Fitment was great. Sound was exactly what I wanted even with my xpipe/resonator delete. Was afraid it'd be poppy with it but it has clean loud sound. Definitely not the loudest exhaust but that's not what I wanted.

    NeverEnough

    Year: 2015 Submodel: GT

    Helpful (0)

  • 5/5

    Installation Time: Less than 1 Hour

    December 09, 2016

    Great product

    Easy to install sounds great no rasp great low rumble

    Strmtrooer

    Year: 2016 Submodel: GT

    Helpful (0)

  • 5/5

    Installation Time: Less than 1 Hour

    June 28, 2016

    SLP LM2 ATAK

    easy to install, follow the directions. mufflers slipped right on, paired it with heartthrob h pipe resonator delete.. My car is a 2016 GT (auto), has real smooth aggressive sound with no drone or raspiness. Only other mod is AirAid MIT with drop in KandN filter. the passenger side tip is a little closer to bumper than I would like, could not get it to move. mufflers are not super loud which will make my wife happy!

    gameovergt

    Year: 2016 Submodel: GT

    Helpful (0)

  • 5/5

    Installation Time: Less than 1 Hour

    December 31, 2015

    GREAT AXLEBACK,NICE SOUND

    Took a chance..... It does fit the convertible perfectly. Most time was measuring to make sure it would fit. Cutting and fitting was a piece of cake. Sounds real good. Not overly loud. I wanted something that sounded good without being loud. It's straight thru but is set up like a resonator to give it a somewhat quieter sound. I took a wild stab on this on and it worked. I'm a Younger-Old GUY(69) that had a 65 which I wish I still had but my 15-5.0(302 in my world) is GREAT. BLACK-BLACKandBLACK . Just wanted something louder than stock but quieter than competition style. I made a good choice.............

    HARLEYGUY

    Year: 2015 Submodel: GT ST. AUGUSTINE, FL

    Helpful (0)

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