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Flowmaster Outlaw Series Axle-Back Exhaust (05-10 GT, GT500)

100+ Reviews
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  • Item #18423
  • MPN# 817511

  • Market Price $487.00
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  • Super Aggressive Flowmaster Outlaw Sound
  • Durable 409 Stainless Steel Construction
  • 2.5" Mandrel-Bent Tubing
  • 4" Polished Stainless Steel Tips
  • Includes Two Flowmaster Outlaw Mufflers
  • Fits 2005-2010 GT, Bullitt, and Shelby GT500
Super Aggressive Flowmaster Sound. Give your Mustang that unmistakable Flowmaster sound with the Outlaw Series Axle-back exhaust system from AmericanMuscle. This system improves exhaust flow using Flowmaster's race-oriented style Outlaw mufflers for that super, aggressive exhaust note your high powered Pony deserves.

Quality Construction. Constructed from durable 2.5" 16 gauge 409 stainless steel tubing for it's corrosion resistant properties the Flowmaster Outlaw Axle-back features two race-oriented mufflers with massive 4.0" diameter polished stainless steel tips for impressive muscle car looks and sound. As an added bonus the tips are embossed with the "Flowmaster" logo for true custom styling.

Application. This Flowmaster Outlaw Series Axle-back exhaust system is designed to fit the 2005 to 2010 GT, Bullitt and the 2007-2010 Shelby GT500 Mustangs for both great looks and great sound.

Technical Note: Americanmuscle recommends adding the 2005+ Mustang 304 Stainless Steel Exhaust Hanger Kit from the drop down option above, to provide more strength, stability and a cleaner installed appearance. If you have a 2007 Mustang you may need the kit for correct installation.

Fitment: 2005 2006 2007 2008 2009 2010 Details

What's in the Box
  • (2) Muffler assemblies
  • (2) Clamps
Installation Info
Tech Specs
Axle-Back Exhaust Specifications
Piping Material: 409 Stainless Steel Tip Material : Polished Stainless Steel
Piping Size: 2.5" Tip Size: 4.0"
Muffler Type: Straight-through Fitment: 2005-2010 GT, Bullitt and Shelby GT500
Will it fit my Mustang?
  • Bullitt - 08, 09
  • GT - 05, 06, 07, 08, 09, 10
  • GT500 - 07, 08, 09, 10

Most Helpful Reviews

2008 Mustang Bullitt

I purchased these for my 2008 Bullitt and they are awesome. These mufflers sound unlike any other exhaust that I have ever heard. They have the flowmaster sound, but there is also a distinct burble sound. ...

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Helpful (4)

Flowmaster Outlaw Series Axle-Back Exhaust

Great Sounding Exhaust I was very anxious to put them on my 2010 GT. They have a classic muscle car growl when idle and they roar like raging thunder when letting the throttle out. After I installed them ...

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Helpful (4)

Overall Rating 4.9 out of 5 stars
Read All 100+ Reviews

Hey everyone I’m Justin with, and today we’re going to be breaking down the Outlaw series Axle-back from Flowmaster for the 2005-2010 Mustang GT. Flowmaster calls this their most aggressive Axle-back system available for the late model 46 Mustangs. This entire kit centers around these two outlaw series mufflers, which to the casual observer, hardly resemble mufflers at all, but rather highly engineered resonant tubes, which are responsible for that super aggressive tone. Like many other Flowmaster kits the Outlaw series features 409 grade steel construction and 2.5” mandrel bent tubing. It also features this very sleek black finish, which is going to be great at resisting corrosion. Everything exits out of these dual 4” polished tips, embossed with that classic Flowmaster logo. Installation of this Axle-back is very straight forward and should only take you about an hour using some basic hand tools. Now let’s hear how the Outlaw series from Flowmaster sounds compared to your factory exhaust.

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17 Questions / 20 Answers

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Flowmaster or bassani Which ones sound better and have less restriction?


  • When it comes to sound it's all what YOU think sounds beter to be completely honest. I have flowmasters on my 1994 Mustang and my best friend has a bassani exhaust setup that sounds pretty nice. I would recommend searching youtube for the different videos. When it comes to axleback however, It won't be as loud as you are probably expecting. I would recommend a completely new exhaust from the headers back. If that's too expensive though this is the cheaper alternative.


    Good Answer (1) (0)

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Need tuning? I drive a 2008 mustang gt and I'm wondering if I get these axle back exhausts will it affect my tuning in anyway or will I need tuning I don't have anything aftermarket like CAI, TURBOS, etc. just wondering Thanks


  • Axle-backs do not require a new tune once installed. Just bolt on and enjoy your new exhaust!


    Good Answer (0) (0)

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Shelby GT Anyone put these on a 2005-2007 Shelby GT? Do they fit the same as stock?


  • yes you will love the sound!!


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finish warranty Is there a warranty on the finish against rust?


  • I have had these on two of my Stang's, an 08 and a 09 and have not had any issue with rust. But then again I live in Virginia and if you are north like Vermont where salt and stuff is used a lot anything will rust.Love em


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  • Outlaw is plenty loud all by itself. If you want to amp it up try some long tube headers paired with an h pipe. But trust me they're good all by themselves


    Good Answer (8) (0)

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Hanger Kit Does a 2006 gt need the hanger kit? Can these be hung properly without it?


  • No, You can use the stock hangers. I just put the same exhaust on this weekend, on my 2006 GT. About an hour in my brothers garage with a floor jack, jack stands, ratchet, two sockets and one wrench.. Simple to do.


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Customer Reviews (100+) Write a Review

Overall Rating 4.9

out of 5 stars

Installation Time:Afternoon

Installation Cost:0-$100

  • Loudness / Volume 4.859903 4.9
  • Exhaust Note 4.903382 4.9
  • Fit & Finish 4.63285 4.6
  • Bang For Your Buck 4.791262 4.8

  • 5/5

    June 10, 2016

    Let them hear you before they see you.......

    I was running the Flowmaster American Thunder Aggressive axle back exhaust on my 2006 GT which sounded good but after having these installed and the excitement of the first turn of the key all I can say is that these Outlaws make the difference in a HUGE way. Deep and throaty with just the right amount of head turning noise and not too annoying. Trust me, you WILL turn heads with these. I am really glad I made the switch. Perfect for my Pony. They sound freakin' awesome! To all you Pony lovers out there if you are thinking about it go for it! You will love them! Thanks American Muscle for the Fast and Free shipping and the great price on these. Worth every penny!


    Year: 2006 Submodel: GT

    Helpful (1) (0)

  • 5/5

    Installation Time: Afternoon

    May 03, 2014

    2006 Mustang GT Outlaws

    The Outlaws are a great choice for anyone who wants a loud exhaust but doesn't want the raspyness of a muffler delete. Fit and finish for me personally wasn't great but I think that is because someone had messed with my stock axle backs because the hangers were way off. But it only took an extra 30 minutes or so to make new hangers so it wasn't bad at all. And now I have nice new non rusted hangers. Overall took about 2 and a half hours or so to install them and get them perfectly lined up. As a little back story, I wanted something that had an old muscle car sound which Flowmaster seems to be the best at. A lot of Mustangs go for that European V8 sound which sounds amazing. But I wanted to go a little old school. And I wanted something loud. Ok so far as sound goes, they are loud but not unbearably loud. The have a little popping on decel or when you rev past about 4k. The exhaust note itself is really good. It's really deep and in the low RPMS and has that old school sound, however it has almost a European V8 mixed with an old school sound, it's really a sound kind of all it's own. And I have to say I really like it. It's old school but with a twist. Overall I am really happy with them, however I can see that if I go with long tubes as well as possibly no cats these may be to loud. If you are just going to do axle backs these are almost perfect in volume. They do kind of break in as time goes on and they get a little more quiet and they get a little more burble to them. Fit I can see as being spot on as long as no one has messed with the factory hangers like they did mine. I would Highly recommend this product.


    Year: 2006 Submodel: GT

    Helpful (2) (0)

  • 5/5

    Installation Time: Less than 1 Hour

    November 04, 2013

    Outlaws are great

    These (and the BBK CAI) were my first mods to my 06 GT. They look great and sound fantastic. I had the luxury of being able to use a lift at a dealer. I'm sure it would have been a little more difficult without the lift. But it was very easy.


    Year: 2006 Submodel: GT

    Helpful (1) (0)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    October 19, 2013

    V6 Outlaw

    It is difficult to know what an exhaust will sound like when you have a V6 with duals, since no one makes it. So you just have to do a lot of research, and these were the best I could find. I was already running Magnaflow Magnapacks, and I must say these made for quite the improvement and created the sound I was searching for all along. There is a bit of drone that makes my louver rattle, but many exhausts do. Would def. recommend this exhaust for fellow sixers!


    Year: 2005 Submodel: V6 Greenville, SC

    Helpful (2) (0)

  • 5/5

    Installation Time: Less than 1 Hour

    April 21, 2013

    The Outlaws

    Killer growl when you put your foot in it, but not so loud that the neighbors are giving you the evil eye while cruising the back streets. The sound attracts lots of attention in parking lots and intersections too, but isn't that why we drive these things?


    Year: 2006 Submodel: GT

    Helpful (2) (0)

  • 4/5

    Installation Time: Less than 1 Hour

    March 05, 2013

    Outlaw exhaust

    I got the outlaws for my girls 2007 GTCS. They look good on the car and sound great. I wanted something that was inexpensive yet would sound good. these are straight through design which I was afraid would be too loud for her. The reviews all said they were extremely loud but I didn't think so. ( of course that's compared to my 2011 GTCS with long tube headers,x-pipe and borla axelbacks) I was almost expecting louder cause of the reviews but the note is a great flowmaster sound and I'm pleased overall. Easy install less than an hour with hand tools.


    Year: 2007 Submodel: GT Oklahoma

    Helpful (1) (0)

  • 5/5

    Installation Time: Afternoon

    April 28, 2012

    Flowmaster Outlaw Series Axle-Back Exhaust

    Great Sounding Exhaust I was very anxious to put them on my 2010 GT. They have a classic muscle car growl when idle and they roar like raging thunder when letting the throttle out. After I installed them you could really tell the difference between the stock mufflers and the new FlowMasters. The exhausts look great , and the material these exhausts are made of is very durable and they should last a long time. Great fitment, installation was an hour and a half and only a few tools were needed. This is a project that can be done in your garage, jacked up in your driveway or on a lift at an auto craft shop. Now when my vehicle rides through any town I leave crowds staring and people compliment me on the sound.


    Year: 2010 Submodel: GT Clinton, MD

    Helpful (4) (0)

  • 5/5

    Installation Time: Less than 1 Hour

    March 08, 2012

    2008 Mustang Bullitt

    I purchased these for my 2008 Bullitt and they are awesome. These mufflers sound unlike any other exhaust that I have ever heard. They have the flowmaster sound, but there is also a distinct burble sound. They work well with the car and turn many heads. I would definitely recommend them to anyone.


    Year: 2008 Submodel: Bullitt Jackson, TN

    Helpful (4) (0)

  • 5/5

    Installation Time: Afternoon

    June 18, 2013

    You will love them...your neighbors won't!

    I am not big on writing reviews but after installing these, I felt AM and Flowmaster deserved a review. First off, thanks AM for getting these to me in less than 24 hours, can't ask for much more than that. Secondly, I am a very amateur wrencher, I've done the majority of the work on my car minus my cam installation, and these went in perfectly. Removing the old hangers is a different story. Removing rusted in bolts, located where only a 9 year old girls hands could reach was a pain, so it took me a little longer than the typical hour long install noted by other reviewers. My suggestion is putting penetrating oil on the (8) bolts the night before, and using anti-seize during the re-install. Now to the good part, I have basic bolt-ons including Steeda cold-air kit, Comp Stage II VSR cams, Kooks long tube headers, and a custom tune. Previously I had Flowmaster American Thunders mounted which I loved but after watching a few re-runs of Monster Garage and hearing the phrase "if you can't hear it before you see it" kicked around, I decided to get something a bit less dainty. Let me tell you, these make my GT sound like an absolute terror coming down the street. Some days I will go out and cruise around in 2nd gear and will be giggling like a little girl the entire way. It is definitely an acquired sound, differing from the AT Flows with their low and lopey sound. These sound more like a semi-truck rolling down the thruway. Like many other reviewers, it does have a decent amount of drone; I'm geared at 4.10's so I get it around 1800-2200rpm. It can be a little annoying but it is easily remedied by giving it a little more gas. And WOT is simply devastating. If you enjoy driving down a city street and setting off every car alarm along the way, or getting the finger by the Audi driver next to you who can't hear his blu-tooth phone call, then the Outlaws are for you.


    Year: 2005 Submodel: GT Buffalo, NY, USA

    Helpful (30) (1)

  • 5/5

    Installation Time: Less than 1 Hour

    April 12, 2012

    Best exhaust ever!

    Loud and throaty!!! if you want sound from an exhaust this is your product!! It still has the flowmaster signature sound note!!! I'm really happy with this purchase!! There is nothing else like it!! It will wake your neighboors and rattle your house windows!! You will turn heads with this exhaust!! My girl friend loves it as well! even on the freeway you can still hear the exhaust note!!


    Year: 2009 Submodel: GT

    Helpful (3) (1)

  • 5/5

    Installation Time: Afternoon

    November 03, 2012

    So much better than....

    I installed the Pype Bombs first and had a rough time with the fit. These are so much better fit and finish, these were easy to align and center in the cutouts and the sound is amazing!!! I think the tone is deeper than the Pypes and don't sound so steel canish. In my opinion spend the extra money and go with Flow Master first.


    Year: 2006 Submodel: GT Mississippi

    Helpful (11) (0)

  • 5/5

    Installation Time: Less than 1 Hour

    October 18, 2013

    No Two Flowmasters Are The Same

    I was running a set of 60-Series Flowmaster axle backs on my 2008 Bullitt for the last year or so. They sounded ok driving around town, but I never liked how tin-canny they sound when you open it up. Still, I tolerated them. But something happened a week ago that sent me looking for a better-sounding exhaust. I was driving with my girlfriend in her car when a Subaru WRX with one of those silly potato cannon exhausts rolled up alongside us. My girlfriend looked over at me and said, "Hey, that sounds just like your car." I was so horrified that I began researching for a new set of axle backs immediately after returning from dinner. After hours of research and sound clips, I was torn between the Pypes Pype Bombs and the Flowmaster Outlaws. I decided to go with the Outlaws based solely on the customer feedback. I crossed my fingers and placed the order. In the back of my mind, I was very concerned that the distinct Flowmaster tin-can sound would still be there in these Outlaws. I was also concerned that the Outlaws wouldn't be much different from the 60-Series set I already had. I was worried that I had made the wrong decision. Let me tell you in no uncertain terms that I am 100% happy with my decision now! The sound of my Bullitt can no longer be compared to a Subaru with a potato cannon! As a previous reviewer said, they don't call these things "outlaws" for nothing. I would estimate that they are at least 40% louder than the 60-Series. They have a very deep, sinister rumble at the lower RPM's, and when you step on the gas they just absolutely ROAR. My daughter was driving behind me last night and she said the inside of her car was vibrating when I would take off from a red light, and I wasn't even putting the hammer down. These axle backs sound so amazing that I have to wonder why Flowmaster would manufacture pipes that are anything less than these Outlaws, and I wonder why any Mustang owner wouldn't want their pony to sound exactly like this. You don't like loud? Then what are you doing in a Mustang? The only bad thing I can say about the Outlaws is that they do not bolt on perfectly with the tips centered in the exhaust cutouts. Yes, they can be adjusted, but Flowmaster should've just manufactured these for the 2005-2009 Mustangs and left out the 2010, which would probably solve that issue. I had them installed by a local shop. I'm not sure where to rate these on the obnoxious scale because it really depends on what kind of neighbor you are. If you want your neighbors to hate you, you can certainly accomplish that with the Outlaws. Run down the street in 1st or 2nd gear and you are sure to scare people out of their underwear. They may tolerate you if you take it easy, but they will still hear you coming or going. If they can't appreciate that American muscle sound, maybe they're not worth the consideration anyway ;) In closing, I highly recommend the Outlaws to any Mustang owner who wants their pony to sound like a lion roaring on the Serengeti Plain. I promise you won't be disappointed.


    Year: 2008 Submodel: Bullitt Lansdale, PA, USA

    Helpful (8) (0)

  • 5/5

    Installation Time: Afternoon

    May 17, 2014

    What will you decide?

    Before purchasing these, you have to ask yourself a question: Do I want to continue to live a mundane, 9-5, stock exhaust life? Or do I want to frighten small children, have women flock to me in droves, and send Camaro owners home crying to their mommies? If you choose the latter, these pipes are for you. Mean and nasty, they sound incredible when driving downtown between buildings. They do drone, so be prepared for that. But it is a small price to pay for the new found prestige,respect and glory that will be coming your way. I had mine installed by by the muffler shop so not sure on the install time for these. Technician pulled them out of the box and said, "Oh man, it's THESE!" After they were installed, all the guys in the next door transmission shop came out to see what the ruckus was all about.


    Year: 2007 Submodel: GT

    Helpful (7) (0)

  • 5/5

    October 16, 2011

    Flowmasters Finest

    Bought these before American Muscle even had them and they are truly unbelievable. I have them on with a bassani x pipe, headers, steeda CAI, and couple other bolt ons and these things scream. Flowmasters loudest product by far. They DO NOT quiet down after 3k rpms like most chambered flowmasters, they get louder. These and slp's are evenly matched in loudness surprisingly but these are better because its flowmaster. Definitely not for daily driving.


    Year: 2005 Submodel: GT Staten Island. NY

    Helpful (7) (0)

  • 5/5

    Installation Time: Less than 1 Hour

    August 28, 2012

    Absolutely Amazing!!

    if you want your mustang to have a "ballsy' aggressive sound this is definitely the exhaust to have! Flowmasters are the best out there and this exhaust proved that. easy install and had it growling in no time. Great product!!!!


    Year: 2005 Submodel: Cobra

    Helpful (7) (1)

  • 5/5

    Installation Time: Less than 1 Hour

    September 27, 2012

    Amazing product! Very aggressive sound.

    VERY loud and VERY awesome!! aggressive through and through. i have received no negative feedback and all compliments. my gf even loves them!! definitely recommend this to anyone!!!


    Year: 2006 Submodel: GT Aransas Pass, TX, USA

    Helpful (5) (0)

  • 5/5

    Installation Time: Less than 1 Hour

    July 08, 2012

    Amazing difference

    These pipes are EPIC! I just bought my '08 GT/CS about a month and a half ago and the only real "problem" I had with it was that it was WAYYY too quiet. After reading reviews and checking ratings, I decided on this axle-back system and I can easily say I do NOT regret that decision. These pipes are LOUD, they turn heads, they demand attention and having done nothing else to the car (yet), it already has the loud aggressive sound I wanted for it. I highly recommend them to anyone. Install time was roughly an hour maybe hour and a half on the lift in our garage. The hardest part is taking off the stock mufflers, I still have the scratches to prove that one!


    Year: 2008 Submodel: GT Annapolis, MD

    Helpful (5) (0)

  • 5/5

    Installation Time: Less than 1 Hour

    January 03, 2013

    Angry exhaust

    Mufflers are real aggressive. They definitely get you noticed. Snaps a neck almost every time. Great sound. Better in person as compared to sound clip.


    Year: 2007 Submodel: GT500 Sayville, NY, USA

    Helpful (5) (1)

  • 5/5

    Installation Time: Afternoon

    November 15, 2012

    Very aggressive sounding!!

    This is an awesome sounding exhaust. I installed it on an '09 GT500. The only issues with installation is removing the stock exhaust. You either have to cut the stock hangers or remove the hanger brackets. Installing and alinging them was really easy. If you like to get attention from bystanders, you'll get noticed with these. At 2000RPM's I'm getting a significant amount of drone inside the car tho, hoping this will lessen when they are good and broke in (for better terms). Completely recommend tho!! This is NOT your typical Flowmaster's, They are BETTER!


    Year: 2009 Submodel: GT500 Fort Rucker, AL, USA

    Helpful (5) (1)

  • 5/5

    Installation Time: Afternoon

    November 14, 2012

    Awesome wishes it sounded this good!

    OMG! OMG! OMG! These things sound absolutely AMAZING!!! I couldn't be happier. They're not just loud, but they give my '10 GT the growl that epitomizes a true muscle car. Installation was pretty easy. Fit was fine. There were some minor scratches on the muffler itself...but nothing anyone would ever see. I did take it by a local shop and had them tighten the clamps...they didn't even charge me. I'm a very happy camper.


    Year: 2010 Submodel: GT Aledo, TX 76008, USA

    Helpful (4) (0)

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