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

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

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    2 Questions / 2 Answers

    Ask a Question

    Video says this system is not compatible with convertibles. Why is that? I have looked at most of your axle back videos on this site and this looks very similar to Roush, which fits verts. So why not this system????

    Fordever

    • The SLP Loudmouth II Axle-back Exhaust is only designed to work with convertibles because of the design of the pipes and flanges. They will not bolt up correctly to a convertible.

      AshleyK

    Helpful (1)

    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 (1)

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    Customer Reviews (28) Write a Review

    Overall Rating 4.9

    out of 5 stars

    Installation Time:Afternoon

    Installation Cost:0-$100

    • Loudness / Volume 3.555556 3.6
    • Exhaust Note 4.962963 5.0
    • Fit & Finish 4.851852 4.9
    • Bang For Your Buck 4.925926 4.9



    • 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 (3)

    • 5/5

      Installation Time: Less than 1 Hour

      October 12, 2017

      Right on the money.

      Exhaust arrived on time, and decided to have shop installed. Took less than an hour and fitment was exceptional. Have a few friends running either muffler delete or resonator deletes (they like real loud) and even they were surprised how good it sounds. Zero drone, just what I was looking for. Well made.

      JH27

      Year: 2016 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      September 08, 2017

      Worth it

      I had straight pipes in the rear along with a x-pipe and the drone was outrageous. I added a set of these and it cleared it right up. Easy to install and look amazing. Sound pretty good as well. Do not regret one bit.

      JustinD

      Year: 2015 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Less than 1 Hour

      September 03, 2017

      Great sound gets louder over time.

      This kit along with an xpipe sound great . 6th gear drone is probably the only thing bad about them. So drop a gear and let her stretch out.

      DDsRedRoxanne

      Year: 2016 Submodel: GT

      Helpful (2)

    • 5/5

      Installation Time: Shop Install

      Installation Cost: 0-$100

      August 30, 2017

      Love it!

      I paired this with the SR X-pipe and I am very happy. I didn't want extremely loud but wanted it louder than stock. Really deep and clean sound with the X pipe. Hardly notice at cruising speed but you can hear it when you get on it! Not raspy at all with the x pipe either. Would highly recommend this setup for someone who doesn't want it too loud and for the money you can't beat it. Start ups are fun now!

      CalebG

      Year: 2016 Submodel: GT

      Helpful (2)

    • 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 (2)

    • 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 (2)

    • 4/5

      Installation Time: Less than 1 Hour

      February 05, 2018

      Low Volume

      Mufflers and tips were great quality. I was running an x pipe/ muffler delete setup but got a fix it ticket here in CA. I decided to try these out and was not completely disappointed. Even with an x pipe these are VERY quiet compared to muffler deletes, Borla, Corsa, Roush, etc. On the other hand, this set up has no drone at all, and neighbors don’t hate me for cold starts at 6 in the morning. If your looking for a slight increase over stock go with these. If you want to make your car heard blocks away go with one of the louder systems out there.

      16GT

      Year: 2016 Submodel: GT

      Helpful (1)

    • 5/5

      Installation Time: Less than 1 Hour

      January 31, 2018

      Love them!

      Combined with an H-pipe it is produces an amazing deep sound. Just the perfect amount of noise.

      MiguelF

      Year: 2017 Submodel: GT

      Helpful (1)

    • 5/5

      Installation Time: Less than 1 Hour

      December 01, 2017

      Muscle sound!

      With the cat delete and a set of resonators and x pipe my car sound like a proper muscle car. Without the resonators everybody look at me LOL

      JavierC

      Year: 2017 Submodel: GT

      Helpful (1)

    • 5/5

      Installation Time: Afternoon

      October 19, 2017

      AWESOME EXHAUST IMPROVEMENT....

      SLP loudmouth mufflers sound awesome with Ford race X-Pipe. I LOVE THE TONE. GET ON IT and IT SOUNDS MEAN. VERY PLEASED.!!!!!!

      MikeH

      Year: 2015 Submodel: GT

      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 (1)

    • 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

      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 (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)

    • 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 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: Shop Install

      Installation Cost: 0-$100

      February 16, 2018

      slp loudmouth II

      sounds really good on the 2017 gt. not too quiet and not too loud. they are just right in my opinion

      bo308

      Year: 2017 Submodel: GT

      Helpful (0)

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