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SLP Loudmouth II Mufflers - Pair (79-04 All)

56 Reviews
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  • Item #23027
  • MPN# 31064

  • Market Price $199.95
  • You Save 4% ($8.00)
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Customer Photos
  • Rich, Throaty Exhaust Tone
  • Straight-Through Design for Superior Flow
  • Designed for SLP Modular Cat-Backs
  • 2.5" Inlet/Outlet Diameter
  • 304 Polished Stainless Steel Construction
  • Sold as a Set of Two
More Power and Sound. SLP's famous Loudmouth II "Bullet Style" race mufflers offer minimal restriction, increased horsepower and an aggressive throaty tone, that is only second to the Loudmouth "shotgun" race resonators for sound.

SLP Modular Design. SLP manufactures their Mustang catback exhaust systems with a unique modular design that allows you to easily and quickly swap out the included mufflers with any of the other SLP mufflers or resonators they make to suit your driving needs.

Superior SLP Construction. The SLP Loud Mouth II "bullet" mufflers are constructed from high hand-polished 304 stainless steel with an embossed SLP logo for great looks, and feature a ceramic-wrapped, perforated core that reduces high-frequency noise and in-car resonance for a rich, throaty exhaust note.

Application. These SLP Loudmouth II Mufflers are designed to easily replace the existing mufflers or resonators in any of SLP's 1979 to 2004 Mustang Cat-Back exhaust systems. The may also be used in the fabrication of custom exhaust systems.

Fitment: 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Details

What's in the Box
Hardware included:
  • None - reuses stock hardware
Installation Info
Tech Specs
  • 2.5" ID/OD
  • 4.5" body diameter
  • 18-3/16" overall length
Will it fit my Mustang?
  • Bullitt - 01
  • Foxbody - 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93
  • Mach 1 - 03, 04
  • V6 - 94, 95, 96, 97, 98, 99, 00, 01, 02, 03, 04
  • Cobra - 94, 95, 96, 97, 98, 99, 01, 03, 04
  • GT - 94, 95, 96, 97, 98, 99, 00, 01, 02, 03, 04

Most Helpful Reviews

Prepare to get noticed!

I bought my 2001 Mustang GT a few months ago with these mufflers already installed by the previous owner. These Loudmouth II's have a very aggressive growl and turn heads every where I go. They have a ...

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Helpful (2)

94 Yellow Mustang GT.

Just the sound I have been looking for. Great buy for the money.

Helpful (1)

Overall Rating 4.8 out of 5 stars
Read All 56 Reviews

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10 Questions / 9 Answers

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loud mouth 1 VS loud mouth 2 99 gt. i have the LM1 system with cat delete, o/r x-pipe, stock manifolds and its a bit to loud/ raspy for me at times. would the LM2 be slightly less but still more than say a flow master (little to quiet)? so I don't have to buy whole new system, just $200 for the mufflers would be worth it. thanks


  • Absolutely, I just made the switch myself for the same reason. You won't regret it. The loudmouth 2's quiet down normal driving an idle but they aren't quiet by any means. All the raspy-ness is gone but under WOT still roar like LM1"s. Under normal driving sounds more like a performance muffler rather then a sloppy straight pipe


    Good Answer (2) (0)

Show 1 more answer Answer This Question I need this answered (0) (0)

Best mufflers What would be the best sounding muffler for mustang gt ?? I want agressive sound , but not to much just driving around. Thanks


  • i would recommend the loud mouth resonators if you have the stock h pipe. thats what i had and it sounded pretty darn good. if you have an x pipe i recommend the loud mouth 2's which are actual mufflers.


    Good Answer (1) (2)

Show 2 more answers Question Resolved

Are these compatible with UPR Products O/R X pipe (no cats) and will the sound scare old people?


  • The SLP Loudmouth II Mufflers have a 2.5" inlet and outlet. Unfortunately I cannot guarantee fitment on a part that we do not carry since we have not been able to test it. But these mufflers paired up with an offroad X pipe should definitely put a scare into anyone behind it!


    Good Answer (0) (0)

Question Resolved

I have a 2002 v6 with flowmaster exaust. Can I put these loudmouth II mufflers on it to make it louder? It is worth it?


  • If you are replacing your Flowmaster mufflers with the SLP Loudmouth II Mufflers, this will definitely increase the volume of your Mustang. I would recommend looking up this exhaust setup to listen to some sound clips first before purchasing.


    Good Answer (0) (0)

Question Resolved

What would be the best sounding muffler for 99-04 v6 mustang?


  • Where this is most certainly up for interpretation, the SLP Loudmouth II Mufflers - Pair (79-04 All) are a great choice if your desired sound is as loud as possible, as these mufflers absolutely help you achieve that goal.


    Good Answer (0) (0)

Answer This Question I need this answered (0) (0)

Can these mufflers simply be switched out with my stock 2003 mustang gt mufflers?


  • There may have to be some cutting and welding for a perfect fit since the SLP Loudmouth II Mufflers will not be the same length as your stock mufflers, but they can be a replacement for your factory mufflers, with modification.


    Good Answer (0) (0)

Question Resolved

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Customer Reviews (56) Write a Review

Overall Rating 4.8

out of 5 stars

Installation Time:Full Day

Installation Cost:0-$100

  • Loudness / Volume 4.2 4.2
  • Exhaust Note 4.566667 4.6
  • Fit & Finish 4.8 4.8
  • Bang For Your Buck 4.366667 4.4

  • 5/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    April 21, 2016

    94 Yellow Mustang GT.

    Just the sound I have been looking for. Great buy for the money.


    Year: 1994 Submodel: GT

    Helpful (1) (0)

  • 4/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    December 01, 2013

    Good mufflers

    I put these on my 86 5.0 along with the x pipes and stage 3 cam amazing tone, not to loud but not quite either... Turn many heads when I drive by good product.


    Year: 1986 Submodel: GT

    Helpful (1) (0)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    May 02, 2013

    Prepare to get noticed!

    I bought my 2001 Mustang GT a few months ago with these mufflers already installed by the previous owner. These Loudmouth II's have a very aggressive growl and turn heads every where I go. They have a much nastier sound than your typical Flow Masters. They're actually pretty quiet when the car is idol, but as soon as you give it some gas, these mufflers roar and crackle with an amazing tone. If you are tired of your quiet stock exhaust, I highly recommend these mufflers. They will definitely make you stand out with a very unique sound that will thrill you and everyone else around.


    Year: 2001 Submodel: GT Virginia, USA

    Helpful (2) (0)

  • 5/5

    March 30, 2011

    amazing sound!

    Had these put on my 04 gt yesterday and all i can say is WOW! have a offroad X with these and the sound is just incredable.


    Year: 2004 Submodel: GT

    Helpful (1) (0)

  • 4/5

    November 05, 2008

    03 GT

    These mufflers sound great with the stock mid pipe! But, I put an O/R H on there and its just too loud. I am going back to a chambered muffler! Great quality, though I do recommend getting the catback.

    Trey B

    Year: 2003 Submodel: GT

    Helpful (1) (0)

  • 5/5

    June 22, 2010

    WAY better than flowmasters

    I put these on my 02 earlier today and i drove around for maybe 30 minutes and i got at least 3 times more looks than i did with my flowmasters. Thank you American Muscle for the fast shipping. Highly recommended for any true mustang lover

    Dennis B

    Year: 2002

    Helpful (23) (3)

  • 5/5

    April 23, 2010


    put these on my 02 gt and they sound great. then i went a step further and put an O/R X-pipe on it and OMG this thing is loud!!! overall a great sounding muffler. thanks AM


    Year: 2002 Submodel: GT

    Helpful (12) (0)

  • 5/5

    June 19, 2010

    5 star product !!!!!

    Great sound, Very pleased, Just the right tone!

    2002 GT

    Helpful (14) (2)

  • 5/5

    December 30, 2010

    A Good Value

    I bought these as a replacement for a bassani muffler that was taken out by a protruding manhole cover. I had some worries about them being a bit loud for my tastes (LT headers, X-pipe o cats), but that proved to be unfounded. They were not too loud and sound good once I have the car tached up, they sound a bit gruff compared to the bassani at low rpms but not objectionably so.


    Helpful (6) (0)

  • 5/5

    July 22, 2010

    Great sound...

    At first I purchased the Loudmouth Resonators - after reading some comments, they were returned (very easy with AM) and picked up these...amazing DEEP sound - welded to stock 2.25 pipes ($80)....great way to go if you don't want to spend $400+ for full CAT system...[FYI: if you don't plan on putting on headers and upgraded x/h pipe....buying the full Catback is a waste of $$$ -]


    Year: 1980

    Helpful (13) (4)

  • 5/5

    March 31, 2010

    best muffler

    had flow masters but when i put these on they way better. add great sound but you need an x pipe and high flow cats to get the best sound.


    Helpful (4) (0)

  • 3/5

    March 12, 2010

    not to shabby!

    they sound GREAT at idle... they are growing on me at the top end... but for the money they are pretty good! I went from no mufflers (cats only) to an off road x and these... and yeah i'm pretty satisfied... but wishing i had the money for a bassani cat back... :) someday...


    Helpful (5) (2)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    March 13, 2014

    Loudmouth II's > Flowmasters

    I did not buy these resonators here, but I did read the reviews and would have bought them here in different circumstances. When I bought my Mustang it already had a custom exhaust kit with Flowmaster mufflers, but to me the sound was a little tame. Everyone says that the Flowmasters are the end-all, be-all in mufflers so I was hesitant to put these on my GT, but based on what I read here and the video that American Muscle put up showing the comparison between the Loudmouth II's and stock, I went ahead and took the plunge. Let me tell you, the difference is night and day. It has that musclecar sound that raises the hair on the back of your neck. While idling, she has that menacing purr. When I step on it to merge onto the highway, she lets out that angry roar that tells everyone around to get the F out of your way! I still need to add on some good headers, but even if I didn't do anything more to it, I would not be disappointed at all going with the sound it has from here on in. If you are hesitating at all to buy these and put them on your Mustang, you're just wasting time you could be driving around with a mean growling 'Stang.


    Year: 2004 Submodel: GT Houston, TX, USA

    Helpful (2) (0)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    February 17, 2013

    SLP Loudmouth 2 Mufflers

    I had flowmaster super 44s and they just werent loud enough for me! I got these SLP mufflers and they are AMAZING! You will NOT be disappointed! I turn heads everywhere with these babys! Got em put on with a BBK O/R X pipe. So nasty!! BUY BUY BUY!!


    Year: 1995 Submodel: GT Seminole, FL, USA

    Helpful (2) (0)

  • 5/5

    Installation Time: Less than 1 Hour

    July 04, 2012


    Well first off i had the slp loudmouth 1 catback with a o/r pro chamber and it was loud i mean loud even at half throttle. It screamed and to me just made me nervous to even pull out of places and this is coming from a 20 year old. So with that said is why i switched to these slp loudmouth 2 thinking it would still be loud but with alot more deeper sound and a nice rumble at cruise, and let me tell you that they are alot more quieter then the 1's. Very quieter it has a nice throaty sound to it but it still isnt what im looking for. If u want something with a LOW rumble at idle and quiet during cruising and scream at WOT then this would be for you. Time so start looking for the right catback all over again.


    Year: 2000 Submodel: GT

    Helpful (2) (0)

  • 5/5

    May 23, 2011

    I am a new customer to SLP!!!

    I always used flowmasters... never again. The sound is way better!! Don't get scared by the name, you will not regret it!!! You can cruise comfortable (still here the music) and when you want to push it... it roars!!! Happy Buyings.


    Year: 1992 Submodel: GT

    Helpful (2) (0)

  • 5/5

    Installation Time: Less than 1 Hour

    November 07, 2013

    Great product!

    I have GT40X heads, comp cam, BBK equal length headers with off road X pipe and these LM2's sound amazing. not raspy and crackly like the LM1's at all. Great sounding pair of glasspacks. they have more of a fuller sound compared to the power-flo mufflers. if you are looking for a great sound without getting pulled over, these are the mufflers for you!!


    Year: 1988 Submodel: Other Queens, NY, USA

    Helpful (1) (0)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: $100-$250

    June 04, 2013

    2002 Stang with LM II

    I still can't believe my ears. These SLP's are awesome sounding.Much better than the Flowmaster 44's I previously had on . Deeper throat sounding. I was pleasantly surprised how quiet they are when the car is at idle. I had wondered if I might wake up the neighbors at 4 a.m. when I leave for work but that is not the case. Thank You American Muscle.\


    Year: 2002 Submodel: GT Rohnert Park, CA

    Helpful (1) (0)

  • 5/5

    Installation Time: Afternoon

    September 09, 2012

    slp mufflers

    great sounding mufflers, not too loud just right for the street


    Year: 2002 Submodel: GT

    Helpful (1) (0)

  • 5/5

    Installation Time: Shop Install

    January 27, 2012


    So loud. I turn so many heads. Awesome. Worth the money! Definitely.


    Year: 2003 Submodel: GT spring hill, fl

    Helpful (2) (1)

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