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Flowmaster Pro Series Axle-Back Exhaust (11-12 GT, 11-12 GT500)

AmericanMuscle no longer carries the Flowmaster Pro Series Axle-Back Exhaust (11-12 GT, 11-12 GT500). Please check out 2010-2014 Mustang Axle-Back Exhaust for an updated selection.
Market Price $587.99 You Save 10% ($59.11)
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  • Item 18415
  • MPN# 819109 kit

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AmericanMuscle no longer carries the Flowmaster Pro Series Axle-Back Exhaust (11-12 GT, 11-12 GT500). Please check out 2010-2014 Mustang Axle-Back Exhaust for an updated selection.

Features, Video & Details

  • Deep, Aggressive Flowmaster Sound
  • Increases Horsepower and Torque
  • Polished stainless steel 4" tips
  • Includes two Pro series mufflers
  • 409 stainless steel construction
  • 18lbs Lighter Than Stock
  • Fits 2011-2012 GT and 2011-2012 Shelby GT500 Mustangs

Review & Installation Video

Review & Install Video

Hey everyone I’m Justin with and I’m taking a look at Flowmaster’s Pro Series axle-back exhaust for your 2011 and up Mustang GT. The Pro Series designed to give you that classic Flowmaster sound yet it’s slightly less aggressive than some of their other options. The exhaust features Flowmaster’s perforated tube style mufflers, which exit through dual 4 inch polished tips. The install should only take you about an hour using standard hand tools. Now that’s take a listen to how Flowmaster’s Pro Series sounds compared to your factory exhaust.

Aggressive Flowmaster Sound. Give your 2011-2012 Mustang GT or GT500 that unmistakable Flowmaster sound with the Pro Series Axle-Back exhaust system. This system improves exhaust flow using Flowmaster's perforated tube style mufflers for that throaty, aggressive exhaust note your high powered Pony deserves.

Increases Horsepower and Torque. This Flowmaster Pro Series Axle-Back exhaust system not only improves the sound of your Mustang, but with it's free flowing design it also improves throttle response and increases horsepower & torque.

Quality Construction. Constructed from durable 3" 409 stainless steel tubing for its corrosion resistance, this Flowmaster axle-back features two Pro series mufflers with 4" diameter polished stainless steel tips that are embossed with the "Flowmaster" logo for true custom styling.

Application. This Flowmaster Pro Series Axle-Back exhaust system is designed to fit the 2011-2012 5.0L Mustang GT and 2011-2012 5.4L Shelby Mustang GT500 for both great looks and great sound.

Fitment: 2011 2012 Details

What's in the Box
  • (2) Muffler assemblies
  • (2) Clamps
Installation Info
About The Brand

About Flowmaster


Tech Specs
Axle-Back Exhaust Specifications
Piping Material: 409 Stainless Steel Tip Material : Polished Stainless Steel
Piping Size: 3" Tip Size: 4"
Muffler Type: Perforated Tube Fitment: 2011-2012 Mustang GT & GT500
Will it fit my Mustang?
  • Boss 302 - 12
  • GT - 11, 12
  • GT500 - 11, 12

Most Helpful Reviews


These axle backs have one of the deepest yet true Mustang notes I have heard. My neighbor has the Roush and it blows him away.

Helpful (2)

Awesome Sound with low drone.

I had a shop install these for me and when the car was started for the first time the sound made the entire shop stop working to checkout what was causing the rumble. My wife's reaction was "That's what ...

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Helpful (1)

Overall Rating 4.7 out of 5 stars
Read All 46 Reviews

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Customer Reviews (46) Write a Review

Overall Rating 4.7

out of 5 stars

Installation Time:Afternoon

Installation Cost:0-$100

  • Loudness / Volume 4.21875 4.2
  • Exhaust Note 4.5625 4.6
  • Fit & Finish 4.5625 4.6
  • Bang For Your Buck 4.5 4.5

  • 4/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    June 07, 2014

    Awesome Sound with low drone.

    I had a shop install these for me and when the car was started for the first time the sound made the entire shop stop working to checkout what was causing the rumble. My wife's reaction was "That's what I'm talking about". The drone is nowhere near excessive and is maximum at about 2000 rpm. Once you get it winding above 3500 rpm the sound is awesome.


    Year: 2011 Submodel: GT Flagler Beach, FL, USA

    Helpful (1)

  • 5/5

    July 30, 2011


    These axle backs have one of the deepest yet true Mustang notes I have heard. My neighbor has the Roush and it blows him away.


    Year: 2012 Submodel: GT

    Helpful (2)

  • 5/5

    January 01, 2011

    2011 GT

    Installed the Hushpowers on my new 5.0. They sound much better than the stock mufflers. A little louder than expected but still not too loud inside the car.


    Year: 2011 Submodel: GT

    Helpful (17)

  • 5/5

    January 27, 2011


    They installed easily, sound and look great. Louder than my brothers '05 with American Thunder and louder than advertised but still great for daily driver! Has a deep muscle car tone, best of all no drone!


    Helpful (20)

  • 5/5

    December 11, 2010

    Hush is good

    Bought this for my 2011 5.0. The car came alive over the stock. It's much louder than stock but I'd say it's a lower-middle sounding volume. Perfect for daily drivers. Also, the big tips fill out the tip area real nice. Gives a better look in the rear end when looking at it from the back, looks great. sounds great.


    Year: 2011

    Helpful (20)

  • 5/5

    Installation Time: Less than 1 Hour

    September 23, 2011

    Great Sound

    Installed these mufflers in about an hour and am really happy with the result. They sound much better in person than they do in any youtube video, a real low rumble that is not intrusive at idle or at cruising speed but really roars at throttle. Several people have commented on being able to hear a lope in the exhaust note at idle due to the low frequencies. Installation is a breeze though I would do it this way vs. the supplied instructions: Remove the exhaust hangars from the car before removing the stock system, once off of the car install the hangars on the new mufflers then put them in place and attach them to the car. If you try to leave the hangars in place and pull the old mufflers out you will be getting very frustrated and I can't imagine what reinstallation would be like! Get them if you want a deep throated exhaust note instead of a higher raspier sound, love them!


    Year: 2012 Submodel: GT TX

    Helpful (5)

  • 5/5

    June 23, 2011

    Cleans Up The Back Nicely!

    The Hushpowers are virtually invisible from the back. They fill out the cutouts on the GT/CS much better than the stock mufflers. Nice deep sound with no rasp.


    Year: 2012 Submodel: GT

    Helpful (5)

  • 5/5

    June 07, 2011

    FM Hushpower axle backs

    ordered these not knowing what to expect sound wise. they sound so deep and amazing! no noticeable SOP power gain but the amazing sound is worth the price of admission.


    Year: 2011 Submodel: GT

    Helpful (5)

  • 5/5

    May 10, 2011


    very nice deep sound a low rpm,reveal the beast inside ,the back hole a fuller now...very good , thank's a.m!!!!

    martin corriveau

    Year: 2011 Submodel: GT

    Helpful (5)

  • 5/5

    Installation Time: Less than 1 Hour

    July 12, 2012

    Amazing Product

    The sound and tone is great, not overbearing, and it only took about 40 minutes to install. Not a noticeable increase in horsepower, but definitely worth the money. Plus, after doing some research, Flow Master is an American company, who uses American materials, and is totally made in the USA.


    Year: 2011 Submodel: GT Colorado Springs, CO, USA

    Helpful (3)

  • 5/5

    August 07, 2011

    Great sound, not too much

    Received the order fast to Canada, well packed, not damaged, i did the installation alone and never did that before, with minimal instruction help, took about 1.5 hour total. Sound is just what i expected from video on youtube. Fit perfectly.

    Pasqual Boucher

    Year: 2012 Submodel: GT

    Helpful (3)

  • 5/5

    August 28, 2013

    Nice improvement over stock

    I got my hushpowers today...3 days from ordering and installed them this afternoon in about 1.5 hr...once I got the car positioned in the garage and tools together. Installation is pretty much as everyone described. You are either going to have to remove the panhard bar or remove the front muffler bracket on the drivers side. I chose to remove the bracket...I never like to remove bars while on jack stands. I've had too many bad experiences in the past with bolts not lining up on re-install. Anyway, the bracket is a little hard to remove because there is a bolt right in the middle above the muffler, but you can get to it with an offset hand wrench. Passenger side is a piece of cake with nothing having to be removed but the muffler. I also used a jack stand to raise and support the intermediate pipes. Getting them out of the way makes removal and install much easier. Installing the flowmasters is really easy. If you wanted to change out these for outlaws or something similar, it would probably only take 15 or 20 min depending on your work area and car lifting situation. A skinny guy could probably do it without raising the car at all. Sound: the sound is definitely an improvement over the stock exhaust but not as loud as people keep saying, in my opinion. If you drove muscle cars from era 64-71, then these won't sound loud...more like a medium aftermarket set on a 70 302 or something. I don't remember people griping about drone back then. By today's standards I still wouldn't say these are loud at all. I had to get out of the car and stand behind the pipes before I could tell a lot of difference. You won't disturb neighbors with these. Regarding the comments about these being too loud...really....if they were any quieter I don't know why anyone would bother. Two things are definitely noticeable that I really like: low rumble at idle and slow crawl is as good as I've ever heard; and when you get on it there is a noticeable muscly growl....just not really loud. Of course you could keep a set of Outlaws and swap them out on days you're feeling aggressive.


    Year: 2012 Submodel: GT GA

    Helpful (2)

  • 5/5

    June 03, 2012

    It's Officially a Mustang Now

    I really like my exhaust. It's was kinda hard driving around a mustang without sounding like one. I installed a SCT-ITSX, JTL CAI, and these mufflers all at once. My mufflers do drone around 2000 rpm. I don't mind the drone, sounds like my 1990 mustang. Step on the throttle and you will be able hear your mustang roar. I may get sick of the drone on long highway drive, but for cruising around they sound awesome!!! I do have some advise about how to remove the stock exhaust. This is guarenteed to be the easiest way. Loosen the exhaust coupler separating muffler and factory cat-back. Use a sawzall to cut the three muffle hangers, cut them as close as possible to the muffler to ensure you do not any wires, hoses, or the factory bolt-in hangers. Pull the remaining hanger pieces out of the rubber hangers. Done. Trying to get the factory muffler hangers out of the rubber mounts any other way is really hard. Just cut them, unless you have some other use for factory mustang mufflers. If you remove the mufflers this way you should be able to finish the project in 30 minutes for a beginner. I spent well over a hour fighting muffler #1. For muffler #2 I cut the hangers and completed in less than 10 minutes.


    Year: 2013 Submodel: GT Butler, PA

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    December 29, 2011

    Perfect Sound and Fitment

    I spent a lot of time viewing videos of various axle-back systems for my 2012 GT before I purchased the Flowmaster Hushpower mufflers. I am very pleased with my purchase. Exactly what I was looking for; perfect deep bass exhaust note down low with a very pleasing growl when the revs build. Loud, but not obnoxious. Exactly how I think a V8 powered muscle car should sound. The units fit perfectly - I followed the installation instructions and had no real problems with the installation once I figured out that if I raised the pipes forward of the axle to the floorboard (using a floor jack) then removed the rear holder from the rubber mount, I could lift the rear of the stock muffler, and pull the muffler out of the front rubber mounts without difficulty (instructions recommended use of silicone spray - I'm sure it helped significantly). Once the stock mufflers were off, installation of the Hushpower units was easy and completed quickly. Once installed, they fill the cutout in the rear diffuser much more completely than the stock units and look sharp.


    Year: 2012 Submodel: GT San Diego, CA

    Helpful (1)

  • 5/5

    Installation Time: Less than 1 Hour

    September 22, 2011

    Great Sounding...NO DRONE!

    I was deciding between the Hushpower and the Borla S-Type. I really could not justify the cost of the Borla, so went with these. After reading on several forums about drone around the 2000RPM range, I was a little apprehensive since that is the RPM I am at when cruising at 75 on the highway. I am pleased to say these have absolutely NO DRONE! The Hushpower exhaust is one of the best sounding exhaust I have heard on the Mustang. At start up they have a deep baritone sound. At partial and WOT they have a very impressive muscle car sound without being obnoxious, and without the gurgling popping sound of other exhaust. I have received a lot of positive feedback from folks about the sound since I installed them. Inside the cabin it was a little loud at low RPM due to the incredible bass these create , but once I removed the sound tube and plugged the hole in the firewall, that problem was resolved. There are absolutely no problems listening to the stereo, carrying on a conversation, or talking on the phone using the BlueTooth system. Installation is a breeze.


    Year: 2011 Submodel: GT

    Helpful (1)

  • 5/5

    July 18, 2011

    9 second mufflers

    These mufflers sound, look and perform great on my Roush TVS blown 2011 GT. With a stock block, converter and tranny weighing 3805 on 3-25-11 in Maryland my car ran 9.89 at 138.39 mph with dots. Search Horseplay Performance on youtube to hear these mufflers under WOT on a 9 second pass!!! I have these same mufflers on my 2012 Boss 302 Laguna Seca and they sound awesome with the side exhaust uncorked! They are the best I have found.

    Rod in TX

    Year: 2011 Submodel: GT

    Helpful (1)

  • 3/5

    Installation Time: Afternoon

    February 14, 2014

    Good but not so good - 2011 GT/CS

    Ordered the Hushpowers (Pro-Series) based on reviews and video on AM and YouTube. The product arrived in a timely manner with some very bad scratches in the paint. No dents or damage other than paint. Used just common sense to install. Loosened the stock mufflers and pipe at the H-pipe connection. No real problems, installed in just over an hour all by myself. One reason I wanted this particular exhaust is that I did not like the looks of the stock mufflers at all. To much silver visible with the GT/CS diffuser. The Hushpowers look great from the rear, cannot image another muffler looking any better. They pretty much dissappear. What I don't like is the UNBEARABLE DRONE. 6 speed auto and the drone is terrible from just below 70 to almost 85. So let the beatings begin, but there is too much noise in the cabin for me. I am almost 50 and it is just not what I was looking for in my sound level. Tone is good, just too loud. I still want to be able to use SYNC and hear the Shaker 1000 without having to use all 1000 watts while cruising down the highway. I am sure this is a good quality product and the looks and fit cannot be beat, but there is just too way too much drone and too much interior noise for me.


    Year: 2011 Submodel: GT Bryant, AR, USA

    Helpful (0)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    October 12, 2013

    Better than I expected.

    The Flowmaster Hushpowers did not disappoint. As a matter of fact they exceeded my expectations. Low rumble much better than other higher pitched mufflers I listened to. Drone at 2K rpm but I'm rarely there for very long. Best sounding mufflers I have ever heard.


    Year: 2011 Submodel: GT Wilbraham, MA.

    Helpful (0)

  • 5/5

    Installation Time: Less than 1 Hour

    August 06, 2013

    Nice mufflers, too much drone.

    The product is well-made and installation took about one hour, but follow instructions exactly. The exhaust sound outside the car was awesome. But, inside, the drone was horrible during acceleration and at freeway speed. I took them off after six months.


    Year: 2011 Submodel: GT Aloha, OR, USA

    Helpful (0)

  • 5/5

    Installation Time: Less than 1 Hour

    July 17, 2013

    Great for a Daily Driver

    Perfect exhaust note, not overbearing noise in cabin.


    Year: 2011 Submodel: GT500 Charlotte, NC, USA

    Helpful (0)

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