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 4.782258 4.8
• Exhaust Note 4.822581 4.8
• Fit & Finish 4.879032 4.9
• Bang For Your Buck 4.814516 4.8

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

  Installation Time: Less than 1 Hour

  May 13, 2016

  slp loudmouth 1s

  As far as product and sound goes.. this exhaust sounds awesome! Very throaty and very loud. But when just cruising has a nice little rumble to it. I was missing a few bolts for the exhaust but had an extra couple bolts so I'm not to worried about it. I have bbk 1-5/8" headers with a bbk offroad xpipe and now the slp loudmouth and I get constant compliments. Great product from AM!

  cleangt

  Year: 2002 Submodel: GT

  Helpful (1) Thanks for your input!

  • Loudness (Volume) 5

    5

  • Exhaust Note 5

    5

  • Fit & Finish 4

    4

  • Bang for your Buck 5

    5
• 5/5

  Installation Time: Shop Install

  Installation Cost: $100-$250

  September 09, 2015

  Best sounding exhaust i've had on a mustang yet

  Had this done by a shop as my stock was rusted on, the install wasn't that expensive at $125 and the exhaust sounds amazing! i couldn't be happier with it. doesn't drone to badly but sounds amazing at the high end.

  MikeD

  Year: 2000 Submodel: GT Downingtown, PA

  Helpful (1) Thanks for your input!

  • Loudness (Volume) 5

    5

  • Exhaust Note 5

    5

  • Fit & Finish 4

    4

  • Bang for your Buck 5

    5
• 4/5

  Installation Time: Afternoon

  August 08, 2015

  Great Exhaust

  This is a great exhaust for the price! Paired this with an H pipe and it sounds amazing. Quiet at idle but when you get on it sounds great! I would recommend this SLP catback for anyone looking for an exhaust on their 'stang.

  RED04V6

  Year: 2004 Submodel: V6 Arlington, Virginia

  Helpful (1) Thanks for your input!

  • Loudness (Volume) 4

    4

  • Exhaust Note 4

    4

  • Fit & Finish 5

    5

  • Bang for your Buck 5

    5
• 5/5

  Installation Time: Full Day

  March 02, 2014

  Sounds awesome!

  Installed with pypes off road x pipe. Sounds great. Yes it's loud very loud. But I love the sound on my v6. It literally roars and bellows at hard throttle. It's got some deep sound to it. Overall I am very happy with this exhaust. Fits perfect,tucks way up and gives plenty of clearance. Highly reccomend drivers that want to be heard. As far as my full day install. I also installed a gt 8.8 rearend. So don't be scared to tackle this slp exhaust.

  hubaduba12

  Year: 2004 Submodel: V6 Savannah, GA, USA

  Helpful (1) Thanks for your input!

  • Loudness (Volume) 5

    5

  • Exhaust Note 5

    5

  • Fit & Finish 5

    5

  • Bang for your Buck 4

    4
• 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 (2) 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 (3) 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 05, 2008

  woo hoo

  The way a muscle car should sound, with stock cats, deep tones and added burble. Awesome! Not too loud at any RPM.

  Randy O.

  Helpful (1) Thanks for your input!
• 5/5

  April 26, 2008

  Sounds great

  After listening to numerous Mustangs and pulling my hair out over making the right choice, I landed on these. All stainless was a huge selling point, and cheaper than the other brands. I wanted a deep, old school muscle car sound; and with my stock H, I got just that. Wow, did it wake my car up. They are not too loud at idle, but when you go, look out! No drone on the highway, just pure, hot, steamy, exhaust, awesomeness.

  Tommy

  Helpful (1) Thanks for your input!
• 5/5

  November 26, 2007

  Get It

  This exhaust scares old people!

  Tang

  Helpful (42) 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 (4) 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

  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 (2) Thanks for your input!

  • Loudness (Volume) 5

    5

  • Exhaust Note 5

    5

  • Fit & Finish 4

    4

  • Bang for your Buck 5

    5
• 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

  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

  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!