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Flowmaster Outlaw Axle-Back Exhaust (15-17 V6)

Item 525581B
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      Review & Installation Video

      The Flowmaster Outlaw Series axle-back exhaust is for the 2015 and newer EcoBoost Mustang owners out there that are looking for an axle-back that'll be more refined and deeper sounding and is made from stainless steel with one of the most budget-friendly price points. So Exhaust for the S550 can get expensive fast, even axle-backs, but this is one of the more affordable options that still offers stainless steel materials. The install for this is easy. It should take you about an hour to complete and it's a two out of three wrenches on the difficulty meter since there is some cutting involved, but, of course, I'll get more into that later. One of the more important things when it comes to shopping for exhaust is going to be the sound. Like I said, consider this as one of the more refined sounding axle-backs for an EcoBoost. It gives more volume and more sound for sure and it's deeper than the stock exhaust, but it steers away from being obnoxious. A lot of times when systems provide a ton of volume increase for the EcoBoost, that's when you really start to get into the import sounding exhaust. If you're looking to steer away from that, this is one of the ones that you're gonna want to consider. Of course the EcoBoost is a four-cylinder turbo car, so that's what it's gonna sound like ultimately. I would call this system a three out of five on the loudness scale, with one being a quiet upgrade and five being a very loud upgrade. You do get more turbo noise with this axle-back since you are opening up exhaust flow around that turbo, and there is an occasional crackle on decel. Still, you don't have to worry about any drone in the interior with this axle-back. You're looking at two and half-inch mandrel bent tubing with this axle-back, which means that Flowmaster did step up the diameter here. The stock exhaust had a two and a quarter-inch diameter. This is made from 16-gauge 409 stainless steel tubing which is gonna be nice for those of you out there that are looking for an exhaust that'll have corrosion resistance and a longer life. Stainless steel will always last longer than aluminized steel would and will hold up better against corrosion. This system finishes with four-inch polished stainless steel tips. Price-wise, this is one of the more affordable options if you look at everything that is currently available. You can expect to pay a little over $400 for this axle-back, which is a good price considering the materials that you have here. Axle-backs for the EcoBoost range anywhere from just over $400 to nearly $1700. And as always if this one doesn't have the sound that you're looking for you have a ton of other options to check out. You're gonna be looking at the typical cut and clamp design with the install for this axle-back since you do need to cut all S550 axle-backs. I'm gonna call this a two out of three wrenches on the difficulty meter but just because of the cutting that's involved. It's nothing too difficult, but I just recommend some eye protection and a fresh Sawzall blade to make things easier. Overall, you're looking at about two hours to get this all done. A lift would certainly make things easier for you here, but the job can be done on jack stands as well if you don't happen to have access to one. Cutting the factory axle-back isn't hard. Just be sure to measure twice and plan and mark where you're gonna be cutting the factory axle-back so you don't make a mistake. You can always mark the axle-back with painters tape if you want to, then use the Sawzall to cut the stock axle-back out. It'll probably be easiest to leave the hangers on the axle-back and just unbolt them from the car. You can transfer them over to the new axle-back then. The new axle-back will come with new clamps for you, so you don't have to worry about that. When you go to install your new setup, it'll probably be easiest to leave everything loose until you have it all lined up and then tighten it down. This is the Flowmaster Outlaw axle-back exhaust for the 2015 and newer EcoBoost Mustang, and you can check it out more online right here at

      Product Information

      Features, Description, Reviews, Q&A, Specs & Installation


      • 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 2015-2017 V6 Mustangs


      Super Aggressive Flowmaster Sound. Give your V6 powered 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.

      Stainless Steel Construction. Constructed from durable 2.5" 16 gauge 409 stainless steel tubing for it's corrosion resistant properties, the Flowmaster Outlaw Axle-Back features (2) 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.

      Cut & Clamp Installation. The installation of this Axle-Back Exhaust requires cutting and removing the stock muffler assemblies, and clamping the new muffler assemblies in place. Clamps and instructions are provided.

      Application. This Flowmaster Outlaw Series Axle-Back exhaust system is designed to fit the 2015-2017 V6 Mustangs for both great looks and great sound.

      Fitment: 2015 2016 2017 Details

      MPN# 817713

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (100+)

      Write a Review

      Ratings Summary

      4.8 out of 5 overall rating from 100+ customers

      Installation Time: Afternoon

      Installation Cost: $100-$250

      • April 06, 2020

        Review shared from Flowmaster Outlaw Axle-Back Exhaust (15-20 EcoBoost w/o Active Exhaust)

        4 2017 EcoBoost - Kendrick


        yep loves these pipes but sometimes i wish i had a v8

        Helpful (0)
      • April 05, 2020

        5 2017 V6 - Adee Installation Time: Shop Install Installation Cost: 0-$100

        Gr8 mod

        First mod on my car Love driving with that super sound. Awesum

        Helpful (0)
      • April 04, 2020

        Review shared from Flowmaster Outlaw Axle-Back Exhaust (15-20 EcoBoost w/o Active Exhaust)

        5 2019 EcoBoost - Gagyuuq Installation Time: Less than 1 Hour

        Great sound

        Good quality sound, not loud but not soft. Just perfect

        Helpful (0)
      • March 31, 2020

        5 2016 V6 - mdrngreaser Installation Time: Less than 1 Hour

        Awesome value

        Awesome value for what you get, super easy to install and great sound for one of the cheaper available kits. Really brought my v6 to life. No drone in the car either once you get to cruising speed.

        Helpful (0)
      • March 30, 2020

        Review shared from Flowmaster Outlaw Axle-Back Exhaust (15-20 EcoBoost w/o Active Exhaust)

        5 2017 EcoBoost - KennyD

        A nice roar for a Eco

        This made my 2017 Ecoboost sound pretty darn aggressive, I love it. Not too loud but also not too quiet!

        Helpful (0)
      • March 02, 2020

        Review shared from Flowmaster Outlaw Axle-Back Exhaust (15-20 EcoBoost w/o Active Exhaust)

        5 2015 EcoBoost - maddieh Installation Time: Less than 1 Hour

        sounds great!!

        was a little hesitant purchasing in the beginning just because i looked up videos of this exhaust and i wasn’t too thrilled with how it sounded.. but after i got it installed it sounds great and i’m super happy with it!! on a cold start you can really tell a difference. highly recommend!

        Helpful (1)
      • January 27, 2020

        4 2017 V6 - MyrtleBeachLife Installation Time: Shop Install


        Sounds great on cold start. Quiet when your not on the gas. Sounds good at low rpm and higher rpms. Around 2k rpms sounds like a honda at least from inside the car. Drone is extreme in that 2k range as well. Hopefully H pipe will help.

        Helpful (2)
      • January 21, 2020

        Review shared from Flowmaster Outlaw Axle-Back Exhaust (15-20 EcoBoost w/o Active Exhaust)

        5 2017 EcoBoost - DominicM Installation Time: Less than 1 Hour

        Awesome exhaust system

        It is a good sounding exhaust for EcoBoost. The sound is awesome doesn’t sound like a lawnmower and looks super aggressive. Pretty easy install as well.

        Helpful (0)
      • January 10, 2020

        5 2005 V6 - Reezy Installation Time: Shop Install Installation Cost: 0-$100

        Amazing Exhaust Sound

        The Outlaws are undefeated!!! The exhaust is very aggressive and has a nice rumble at idle. It is not raspy at all. If you like drone then these are for you because it's plenty of it.

        Helpful (0)
      • November 26, 2019

        4 2015 V6 - BrandonD Installation Time: Afternoon

        A little loud

        Love the sound but is a little louder than I originally expected.

        Helpful (1)

      Questions & Answers (58 answers)

      5 Top Rated Questions

      Does installing the Flowmaster Outlaw Series Axle-Back Exhaust on my 2017 Mustang eccoboost affect the new vehicle warranty from FORD?

      • Hello, Ford explained to me that the only way and after market part would void the warranty is it poorly malfunctioning.

      Helpful (15)

      I have the convertible version of the 2015 Mustang Ecoboost Premium. With this axle-back fit?

      • The Flowmaster Outlaw Series Axle-Back Exhaust is designed to fit both coupe and convertible ecoboost Mustangs.

      Helpful (9)

      is this product legal in the Rio Grande Valley ,Texas

      • Unfortunately, we are not familiar with the local laws and regulations in your city. Please contact your local Department of Transportation, and/or Law Enforcement Agency.

      Helpful (4)

      I live in California. If i put this on, will i still pass smog? This is probably the only reason holding me back. I have a 2017 v6 mustang.

      • The Flowmaster axle backs will pass smog testing however you will want to check your local laws on noise restraints to be safe.

      Helpful (4)

      Is this system compatible with the Flowmaster Scavenger series Y-pipe?

      • The Flowmaster Scavenger Series Cut and Clamp Resonator Delete Y-Pipe, Item 389694 is compatible with these axle-backs.

      Helpful (4)
      10 More Questions
      Everything comes as shown in the photo? 1 answer
      Does it require a computer tune? 1 answer
      Is it absolutely necessary to cut and bolt on or can I get away with not cutting at all? 1 answer
      I live in California and was wondering if this exhaust system is CARB certified. Would it pass smog check if I install it on my car? 1 answer
      Would this fit my 2019 EcoBoost Mustang? 1 answer
      I want to get a resonator delete and I was wondering if this would fit on with a MRT y pipe resonator delete? 0 answer
      Will the sound be above 95dB if put on 2019 Ecoboost Mustang? Is there any drone inside at 2000 RPM? 1 answer
      Will this pass emissions inspection in Virginia? 1 answer
      I installed this and for some reason my car throttle seemed slower why is that ???? 1 answer
      I saw in a previous response that this is CARB legal and was wondering if I could get a CARB sticker 1 answer

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (2) Muffler Assemblies

      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-throughFitment:2015-2017 V6

      Will It Fit My Mustang

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