SLP Loudmouth Cat-Back Exhaust (99-04 GT, Mach 1)

Customer Reviews (100+) Write a Review

Overall Rating 4.9

out of 5 stars

Installation Time:Afternoon

Installation Cost:$100-$250

• Loudness / Volume 4.776119 4.8
• Exhaust Note 4.828358 4.8
• Fit & Finish 4.850746 4.9
• Bang For Your Buck 4.798508 4.8

• 5/5

  November 26, 2007

  Get It

  This exhaust scares old people!

  Tang

  Helpful (43) Thanks for your input!
• 5/5

  April 13, 2009

  Just Perfect

  Dont listen to anyone who tells you these are too loud. They are not.They are perfect. They do \'shout\' dont get me wrong and people will move out of your way (i love when that happens to me :-) but they are not obnoxious, I contemplated for the longest time on which catbacks to install on my 04 V8 GT. Got them put a week ago went down to the NJ shore this weekend...The drive was brilliant... Definitely recommended. PS they might be \'Too loud\' if you throw on and O/R pipe or something but i have the stock mid pipes and they are great. if you like something with a bite,these are it and AM ships right on time every time. I do all my \'car\' shopping out here. Kudos to AM and to my cat backs. cheers

  BumbleBee

  Year: 2004 Submodel: GT

  Helpful (34) Thanks for your input!
• 5/5

  January 31, 2010

  This exhuast = BA

  This exhaust was very easy to assemble, and very easy to line up. the tubing is already notched for easy clamping. Plus, the sound is very nice and loud. It gives my car a very muscular sound. So in all that is why i say this exhaust = Bad A**

  Robert

  Helpful (19) Thanks for your input!
• 5/5

  August 13, 2009

  They Bark!

  I really like this exhaust. I also added a BBK ceramic coated long tube header and BBK shorty H-pipes with the cats and this system is the perfect addition. When you don't get on it, it's a "medium" mellow tone. Not too loud, but loud enough. When you get on it, it flat out barks! I mean it's loud! I love it!! It reminds me of my GTO with headers and glass packs from years gone by. I do recommend this combination, if you're into the sounds of the "old days".

  Don

  Helpful (17) Thanks for your input!
• 5/5

  August 16, 2010

  03 stang

  sounds nasty, but in a good way really you will love this cat back. took a wile to take off the stock exhaust, nuthing a hak saw cant take care of. the loud mouth went on very easy but i have a friend that has lift. good mean sound when you start it turns a lot of heads im the parkin lots. its not loud unless you want it to be cops dont even look at you. but when munch on that gas you will get chills. the only problem i have with it is when i drive down the interstate at about 2000 it has a lot of exhaust sound in the cab sounds good at first but gets a little old but all in all i love it. thanks AM

  novotony

  Year: 2003

  Helpful (10) Thanks for your input!
• 5/5

  July 22, 2008

  hear me roar

  They are bad ass. I was pulled over by the Ohio state troopers just to tell me how bad ass my 2004 mustang gt sounds with the SLP loudmouth exhaust installed. It was and is an awesome system.

  p simms

  Year: 2004 Submodel: GT

  Helpful (7) Thanks for your input!
• 5/5

  December 21, 2010

  Nice

  Catback with catted x-pipes sounds awesome. Quiet when under 2k rpm but after it roars!!! Travel down highway and no annoying sounds. Hear radio just fine. Thank you A&M for good product to reach my door as promised.

  Jesse

  Helpful (5) Thanks for your input!
• 5/5

  February 16, 2010

  Woth Every Penny

  One word for this Exhaust system "Perfect". Give your car the sound that gives people shiver. TOP NOTCH SYSTEM!!!

  adam demarco

  Helpful (5) Thanks for your input!
• 5/5

  Installation Time: Shop Install

  Installation Cost: $250-$500

  April 06, 2013

  Loudest Exhaust Ever!!

  If you want semi-loud, try looking elsewhere. This exhaust is extremely loud and i love it. Some people do think its too much when paired with long tubes and off road x pipe. When we started the car after installation for the first time, I smiled from ear to ear and jumped around like an uncontrolled idiot.

  ceeunique

  Year: 2000 Submodel: GT

  Helpful (4) Thanks for your input!

  • Loudness (Volume) 5

    5

  • Exhaust Note 5

    5

  • Fit & Finish 5

    5

  • Bang for your Buck 5

    5
• 2/5

  Installation Time: Shop Install

  March 29, 2012

  Not what I was expecting...

  After reading through all of the reviews and seeing how happy people were with this exhaust I was not hessitant to buy it myself. After the install however I was blown away by how LITTLE the sound of my exhaust actually changed, It's barely louder and at higher RPMs I think it sounds terrible. Through about 1-2.5 Grand It sounds ok But after that the tone and volume drop substantially. Maybe it's just my Mustang but if your expecting a loud exhaust, it's not here.

  Nicholasjay52

  Year: 2004 Submodel: GT South Beloit, IL

  Helpful (4) Thanks for your input!

  • Response from AmericanMuscle

    I'm sorry you're disappointed in the overall sound of this catback after installing. This system is one of the louder options available and I've never heard feedback on the lack of sound produced. Adding the SLP Catted X-pipe, SKU 23008, might help you obtain the sound you are looking for and provide you with better airflow and power gains at the same time. I'd recommend contacting SLP directly as well and chat with them about your install to see if they have any insight as to why your system isn't performing as expected. Hope this helps!

    Lisa , Content Specialist
    

  • Loudness (Volume) 3

    3

  • Exhaust Note 3

    3

  • Fit & Finish 5

    5

  • Bang for your Buck 2

    2
• 5/5

  Installation Time: Afternoon

  September 23, 2011

  awesome sound

  if you want to be loud and heard, this is by far the best system to go with. fitment was simple had no issues with installation.

  Featured

  AlexAM

  Year: 2001 Submodel: GT Aston, PA

  Helpful (4) Thanks for your input!

  • Loudness (Volume) 5

    5

  • Exhaust Note 4

    4

  • Fit & Finish 5

    5

  • Bang for your Buck 5

    5
• 5/5

  June 13, 2009

  2004 V6

  I recently just put this cat back on my car along with a pypes catted X and BBK shorty headers and its louder than any other modded V6 I\'ve ever heard. No joke when i rev this B*TCH up she screams her ass off. GREAT PRODUCT THANKS AM!

  Chris

  Year: 2004 Submodel: V6

  Helpful (4) Thanks for your input!
• 5/5

  April 07, 2008

  2003 3.8L V6

  Exhaust was easy to install once I got my v6-v8 adapter (H-pipe) welded on. I was a little unsure about the sound I was going to get...with my car being a v6, and with my friend and his MAC y pipe exhaust sounding nice, I didn\'t know what to expect. When the exhaust was done, his jaw was on the ground and he wanted my same SLP loudmouth setup.

  Jeff

  Year: 2003 Submodel: V6

  Helpful (4) Thanks for your input!
• 5/5

  Installation Time: Afternoon

  October 02, 2011

  It took a little over two hours to cut off the old exhaust and install the new ones

  It's a great product that sounds really good. I thought they would be too loud but ended up being just what I been looking for. These cat backs will make heads turn. I'm sure with headers it would sound even better. I had Borla Stingers on my old mustang, they sounded good but these sounds way better!

  TSTELL

  Year: 2004 Submodel: Mach 1 Baton Rouge, La.

  Helpful (3) Thanks for your input!

  • Loudness (Volume) 5

    5

  • Exhaust Note 5

    5

  • Fit & Finish 4

    4

  • Bang for your Buck 5

    5
• 5/5

  December 11, 2010

  slp loudmouth 1

  this catback and an o/r xpipe is perfect if you want the attention! iam not goin to lie but you can hear my o3 Gt from blocks away! slp is great! AM is great

  jesus sanchez

  Helpful (3) Thanks for your input!
• 5/5

  July 21, 2016

  LOVE this catback!!!

  So I just bought a 2004 Mach 1. Previous owner had a Bassani catted x-pipe with Magnaflow Street catback. Meh, it was ok, too stock sounding for my tastes. I've had SLP's before on older GT's, so I knew what I was getting into. But WOW, this catback paired with the Bassani x-pipe is insane! I never heard that amazing bubbly 4 valve idle on my car until I put this SLP catback on. If you've ever heard an 03-04 Cobra idle, this brings out that same sound in your 4 valve. Surprisingly there really isn't much drone considering how loud it is on the outside. But mash your right foot down and this baby SCREAMS! And of course, AmericanMuscle delivered FOR FREE within 3-4 days. Couldn't ask for a better price or better service. Thank you!

  speedddemon0712

  Year: 2004 Submodel: Mach 1

  Helpful (2) Thanks for your input!
• 5/5

  Installation Time: Shop Install

  April 13, 2012

  Be Heard!

  I like it when i hear other American Muscle cars rolling down the street!. Now with this new cat back system paired with the matching X-pipe, i get a lot of attention. It sounds wonderful and looks awesome with the SLP logo on the tips! And for that added thrill factor hit up a parking structure, rev it up and let your loudmouth set off EVERY car alarm in the garage! Tested and Proven to give you chills!!!

  Phialpha288268

  Year: 2001 Submodel: GT Las Vegas, NV, USA

  Helpful (2) Thanks for your input!

  • Loudness (Volume) 5

    5

  • Exhaust Note 5

    5

  • Fit & Finish 5

    5

  • Bang for your Buck 5

    5
• 5/5

  September 12, 2010

  Great System

  This product is a great value. Choosing you exhaust is a difficult decision. I choose SLP lm1 for my 04 mach 1, and I don't regret it for a second. SLP has a rep of being very raspy and loud. Listen, yeh it's loud, but it's an amazing sound. I turn heads everywhere, and constantly get comments of how nice and mean my car sounds. When you pair this cat-back, with a catted x-pipe, it really comes to life. Highly suggest this product.

  Kevin

  Year: 2004

  Helpful (2) Thanks for your input!
• 5/5

  March 31, 2008

  2002 mustang gt

  Very easy to install. Took about an hour to take the old pipes off and put new ones on. If you like loud, raspy shifts, and a mean ass rumble, this is definitely the way to go. Two thumbs up!

  greg

  Year: 2002 Submodel: GT

  Helpful (2) Thanks for your input!
• 5/5

  Installation Time: Afternoon

  December 09, 2016

  LOUD!!!

  This exhaust is soooooooooooo loud. My neighbors hate my car even more than before.

  ChestyLaRue

  Year: 1999 Submodel: GT

  Helpful (1) Thanks for your input!

  • Loudness (Volume) 5

    5

  • Exhaust Note 5

    5

  • Fit & Finish 5

    5

  • Bang for your Buck 5

    5