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SLP Loudmouth Cat-Back Exhaust (99-04 Cobra)

Market Price $599.95 You Save 4% ($24.00)
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  • Item 23005
  • MPN# M31006

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Features & Details

  • Rich, Throaty Exhaust Tone
  • Loudmouth "Shotgun" Race Resonators Included
  • Versatile Modular Design
  • 2.5" 409 Stainless Steel Tubing
  • 3.5" Polished 304 Stainless Steel Tips
  • Fits 1999 to 2004 SVT Cobra Mustangs
More Power and Sound. This SLP system includes SLP's infamous Loudmouth "shotgun" race resonators that offer virtually no exhaust flow restrictions to free up more horsepower and to produce the most aggressive sound possible.

Modular Design.   SLP's unique modular design allows you to quickly and easily switch out the mufflers or resonators to suit your driving needs. Along with the included resonators, the Loud Mouth system is compatible with all SLP mufflers and resonators including the bullet-type Loud Mouth II and the traditional-style PowerFlo Muffler.

Superior SLP Construction. This SLP Cat-Back system is made from mandrel bent 2.5" 409 stainless steel tubing for its excellent non-restrictive flow characteristics and long life. The system ends with a brightly polished 304 stainless steel 3.5" tips, that are electro-marked with the distinctive SLP logo, giving a great finishing touch and a show quality look.

Application. Designed to be a direct bolt on, this SLP Loudmouth catback will bolt straight up to the factory Mid-Pipe without any modifications required on the 1999 to 2004 IRS equipped SVT Cobra Mustangs to give it a rich, throaty sound.

Fitment: 1999 2001 2003 2004 Details

What's in the Box
Hardware included:
  • (8) 2.5" exhaust clamps
Installation Info
Tech Specs
Cat-Back Exhaust Specifications
Piping Material: 409 Stainless Steel Tip Material : Polished 304 Stainless Steel
Piping Size: 2.5" Tip Size: 3.5"
Muffler Type: Straight-through Fitment: 1999-2004 Cobra Mustangs
Will it fit my Mustang?
  • Cobra - 99, 01, 03, 04

People Who Bought This Item Also Bought

Most Helpful Reviews


I have an '03 cobra with 25,000 miles. The stock exaust was good, but I was looking for more of a rumble and the slp took care of that. Removal and install took about an hour in my driveway. Now my cobra ...

Read More
Helpful (6)


I can compare this cat back system to most of the other cat back systems that I have personally used. (minus Borla Stingers). Install 35 min on a lift (and the stock cat back can be fully retained and ...

Read More
Helpful (3)

Overall Rating 4.8 out of 5 stars
Read All 34 Reviews

Customer Photos (11) Submit Your Photo

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6 Questions / 9 Answers

Ask a Question

I have Kooks Headers and Kooks X Pipe will this bolt up together and not leak?


  • Hello, That is correct these are designed as a system.


Helpful (0)

Is this the LM1's or LM2's?


  • These are the LM1's.


Helpful (0)

SLP loudmouth or Borla ATAK?!?! and does this drone or sound bad w/o the resonators?


  • The SLP Loudmouth Cat-Back Exhaust feature a deep, throaty exhaust tone. The "shotgun" resonators that are included have virtually no restrictions which will offer more power and an aggressive sound. Without the resonators, you may receive a louder sound without some tone. The Borla ATAK Cat-Back Exhaust (99-04 Cobra), item # 29016, ( feature an extremely aggressive muscle car sound. These do not come with resonators like the SLP's do. Both of these Exhaust's should not feature drone.


Helpful (0)

Does the car need a re-tune with this catback? I have already have a CAI on the car.


  • The SLP Loudmouth Cat-Back Exhaust (99-04 Cobra) will not require a re-tune.


Helpful (0)

Do I have to install the resonators? Can I just leave out the resonators on this catback system so I can get more of a louder and throaty sound to this exhaust system?


  • Trust me you'll want to install the resonators with the kit for the best sound and fitment.


Show 1 more answer Helpful (0)

Does this come with everything I need to install? Do I need any extra hangers or clamps or anything else with this system?


  • This SLP exhaust kit comes with everything you will need for the install!


Show 2 more answers Helpful (0)

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Customer Reviews (34) Write a Review

Overall Rating 4.8

out of 5 stars

Installation Time:Less than 1 Hour

  • Loudness / Volume 4.782609 4.8
  • Exhaust Note 4.913043 4.9
  • Fit & Finish 4.652174 4.7
  • Bang For Your Buck 4.608696 4.6

  • 5/5

    May 19, 2010


    I have an '03 cobra with 25,000 miles. The stock exaust was good, but I was looking for more of a rumble and the slp took care of that. Removal and install took about an hour in my driveway. Now my cobra sounds like a mustang should. LOUD.


    Year: 2003

    Helpful (6)

  • 4/5

    September 25, 2010

    Do You Like Loud?

    I put this "Loudmouth" exhaust on in place of my Flowmaster cat back system along with SLP's X-Pipe, and all I can say is "WOW" is this loud!!. You really notice the difference during acceleration and even when the car is at idle. I did notice it took away some top end, but the car may need to be re-tuned...A+ to AM for fast shipping to my doorstep!

    Mike Moyer

    Helpful (3)

  • 5/5

    June 30, 2010

    04 COBRA

    I can compare this cat back system to most of the other cat back systems that I have personally used. (minus Borla Stingers). Install 35 min on a lift (and the stock cat back can be fully retained and saved) I had no issue with fitmint; straight forward and simple install. Im running stock headers, Magna flow high flow X-pipe with this catback. I wanted LOUD and my setup delivers hands down...A+ product and a shout to AM for quick delivery


    Year: 2004

    Helpful (3)

  • 5/5

    June 11, 2009

    VERY loud!

    I have a 2003 Cobra with BBK long tubes and BBK short off road x pipe. Then I installed this system and man is it great. Probably the loudest system out there and noticable hp gains. Bottom line LOUD, great hp for the money and easy to install


    Year: 2003

    Helpful (3)

  • 5/5

    August 05, 2008

    Great Product

    Installed with SLP catted X on my 03 Cobra. Simple install and GREAT sound. Excellent power for the money. DO NOT PURCHASE if you want a quiet system. I have an 01 GT with off road H and Flows and this system is louder!


    Year: 2003 Submodel: Cobra

    Helpful (3)

  • 5/5

    Installation Time: Afternoon

    November 04, 2013

    Amazing exhaust!

    Sounded amazing on my cobra! Not for people who don't like extremely loud exhaust! Very deep shotgun at around 3 thousand that makes you tingle !


    Year: 2001 Submodel: Cobra Long Island ny

    Helpful (2)

  • 5/5

    November 23, 2010


    this is the best sounding and best performing exhaust i have ever had and i own three mustangs easy install


    Helpful (2)

  • 4/5

    September 01, 2009

    Great exhaust

    Some pieces required a bit of pressure to get them to go together,but great sound and hp gains.


    Helpful (2)

  • 5/5

    Installation Time: Less than 1 Hour

    December 15, 2016


    Sounds beastly, I was scared it was going to be too loud but it sounds perfect. Good solid deep tone and a nice crackle in the higher rpms.


    Year: 2001 Submodel: Cobra

    Helpful (1)

  • 5/5

    July 19, 2016


    Easy to install, good price and awesome sound!! Thanks AM


    Year: 2004 Submodel: Cobra

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    March 07, 2016

    SLP makes a Great Product

    I have owned SLP exhaust before and never had a problem with it the fitment has always been great. I currently had Bassani exhaust on my car and it just fell apart. So I went with a exhaust that I have used before and was very pleased with


    Year: 2003 Submodel: Cobra

    Helpful (1)

  • 3/5

    Installation Time: Less than 1 Hour

    January 13, 2016

    Great cat-back but it is lacking in aesthetics

    The catback as far as fitment and ease of install is great. I love the sound. The major drawback that isn't very apparent from the picture is that the only parts of this catback that have any shine whatsoever are the resonators and the tips. One of the best parts about an IRS is having the pipes under the car really shined up as it looks amazing from behind. I don't know if SLP has changed anything, but the piping itself is extremely dull with lots of marks from the mandrel bending. It looks almost like mild steel piping. If it had a shine out of the box comparable to the Borla it would get 5 stars all day.


    Year: 2003 Submodel: Cobra Griffin, GA

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    October 29, 2015

    SLP Loudmouth LOUD!!!!

    OMG!!!!! All I can say is very loud sounding exhaust. If you like loud then get this exhaust. I freaking love this exhaust. No problems at all, fitment is good, awesome sounding exhaust.


    Year: 2003 Submodel: Cobra Bryan, Texas

    Helpful (1)

  • 4/5

    Installation Time: Less than 1 Hour

    January 06, 2015

    tips and mufflers look great rest not quite as clean looking

    Loudmouth sounds great! Installation was easy. Mufflers and tips look great, the rest of the pipes look generic, not stainless steel. Thought it was all stainless steel like the MagnaFlow system. But sounds great and love the sound!


    Year: 2003 Submodel: Cobra Riverside, CA, USA

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    July 28, 2014

    SLP LM1 cat back

    This cat back installed very easily. I paired this cat back with a bassani off road x pipe. Incredibly loud and I love every bit of it. Shipping was very fast. No complaints.


    Year: 2001 Submodel: Cobra Columbus, OH, USA

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    March 17, 2014

    SLP catback, MAC catless prochamber

    I installed the SLP catback with my MAC prochamber to change the sound a little from the rest of the pack and wow i got the loud aggressive rumble and pop I want yet can idle the car down and still pass the cops! Only a 5/8 socket on 1/2 in. drive ratchet and a 15 mm combo to install!!! Thumbs up AM!


    Year: 2003 Submodel: Cobra Rochelle

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    April 17, 2013

    This is a must have!!!

    I have a 2004 Cobra that had flowmasters on it. It just wasn't loud enough or had a good tone to it. The slp loudmouth is definitely louder that's for sure. It only took a half hour to install on a lift. Definitely worth the money and people will notice you more. Thank you American Muscle.


    Year: 2004 Submodel: Cobra Columbia, MD

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    March 21, 2013

    SLP Loud

    Great exhaust system... I'm still running stock H pipe but still can tell a huge difference in the sound. Well worth the money. Took me about 1hr to install. Suggest getting a tuner to really feel the difference in HP.. Can't wait to purchase the SLP X pipe :-)


    Year: 2004 Submodel: Cobra

    Helpful (1)

  • 5/5

    Installation Time: Afternoon

    September 18, 2012


    Great product!! Easy to install and adjust. Came with great instructions and nice packaging. Love the sound and looks.... And the stickers


    Year: 1999 Submodel: Cobra Ytown ohio

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    August 03, 2012

    OMG get this

    This is the best sounding exhaust I've had. Had many flowmaster and magnaflow systems and this is hands down the best IMHO. The fit is perfect took me 45 min to install no leaks on 1st attempt. I read in the install to cut ends off factory hangers, nonsense put dish soap on them and they pop right out. I put my car on ramps(not jack stands) and couldn't have been easier. You do not have to take wheels off neither. So easy... Buy now!


    Year: 1999 Submodel: Cobra Alabama

    Helpful (1)

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