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Flowmaster American Thunder Axle-Back Exhaust (05-09 V6)

Item 18404
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      Review & Installation Video

      Product Information

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


      • Aggressive Flowmaster 60-Series Delta Flow Sound
      • Polished Stainless Steel 3.5" Tip.
      • Durable Aluminized Steel Construction.
      • Includes One Flowmaster Muffler
      • Fits 2005-2009 V6 Mustangs.


      Flowmaster Sound . The Flowmaster American Thunder Axle-Back exhaust system will improve your 2005-2009 V6 Mustangs exhaust flow for an increase in power and a throatier muscular exhaust note with their patented chambered designed muffler.

      Quality Construction. Constructed from durable 2.5" 16 gauge aluminized steel tubing for it's corrosion resistant properties the Flowmaster axle back features a specialty 5" X 10" chambered 60 Series Delta Flow American Thunder muffler with a 3.5" diameter polished stainless steel tip for muscle car looks and sound. As an added bonus the tip is embossed with the "Flowmaster" logo for true custom styling.

      Fitment. This Flowmaster American Thunder Axle-Back exhaust system is designed to fit the 2005-2009 4.0L V6 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 Details

      MPN# 17421

      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: 0-$100

      • September 05, 2019

        4 2006 V6 - BentleyZ Installation Time: Less than 1 Hour

        Great tone but still a v6

        This exhaust sounds great and a must have. Adds a lot of volume and a lot of tone. Loud when you want it to be, or can sound stock. It does have a trumpet type sound occationally, usually right after a cold start. Sounds great but you’re not fooling anyone, sounds like a v6 not a v8.

        Helpful (1)
      • March 22, 2019

        5 2005 V6 - Brad Installation Time: Shop Install Installation Cost: $100-$250

        Awesome Muffler

        Just had this muffler installed on my 2005 mustang convertible v6. It sounds great! It has a nice deep sound to it. It's not real loud at idle but when you give it gas it's got great sound. It sounds similar to a v8. I usually do all the work on our cars but I just had surgery so I had a muffler shop do it. They charged me 120 which I think was overpriced.

        Helpful (1)
      • March 19, 2019

        5 2005 V6 - GoodTimes Installation Time: Less than 1 Hour

        Worth it!

        I was looking for something to spice up my car, that wouldn’t be an entire project. Found axel back exhausts and was intrigued. I watched tons of videos on the sound of each style, the installation, and comparison. I landed on the American Thunder from Flowmaster and I was not disappointed in the slightest. I love the way this has made my car sound. Completely stock, but it sounds so much better than the stock muffler it comes with. I highly recommend this.

        Helpful (1)
      • January 27, 2019

        4 2006 V6 - JimM Installation Time: Less than 1 Hour


        Muffler arrived quickly and and packed in foam, and supplied with a good quality clamp. Installation was easy and everything lined up well. Sounds good without excessive volume. Good product.

        Helpful (1)
      • January 10, 2019

        4 2006 V6 - AnthonyC Installation Time: Less than 1 Hour

        Great product.

        Installing this took no time at all. It sounds and looks great.

        Helpful (2)
      • December 18, 2018

        4 2007 V6 - ChandaH Installation Time: Less than 1 Hour

        I like it

        It has a nice sound. It’s not to pound when you’re idle. Reving has a very nice sound too.

        Helpful (2)
      • November 19, 2018

        5 2008 V6 - TywainH Installation Time: Less than 1 Hour

        Beautiful install!

        Installed in less than an hour. Love the sound flow it brings to my mustang.

        Helpful (2)
      • October 25, 2018

        5 2007 V6 - AndreP Installation Time: Afternoon

        Very Satisfied

        I’ve had a Flowmaster exhaust on a previous vehicle I owned and know the quality, fit and finish of their products. This one did not disappoint. Now my V6 has that undeniable Flowmaster sound. I would highly recommend this product.

        Helpful (2)
      • September 25, 2018

        5 2007 V6 - JoshC Installation Time: Less than 1 Hour

        Good sound

        Did not take long. Hardest part was removing the old muffler.

        Helpful (2)
      • September 13, 2018

        5 2005 V6 - JuanJ Installation Time: Less than 1 Hour


        Sounds great! Not too loud but loud enough to turn some heads...

        Helpful (2)

      Questions & Answers (22 answers)

      5 Top Rated Questions

      I bought my mustang with this already installed, is there a way to make it more aggressive and louder sounding without totally replacing it?

      • There is no way to modify the sound of the exhaust directly, other performance parts would have to be added to the vehicle to change the volume/tone.

      Helpful (0)

      Is there any Horsepower gained compared to a stock V6?

      • There really would not be any horsepower gain with these. At most you may see a gain of 1-2 horsepower.

      Helpful (0)

      My mustang is straight piped and I had a piece of pipe welded where my muffler used to be. Will I still be able to install this product?

      • A significant amount ofalteration would be needed to install this item due to your existing modifications. 

      Helpful (0)

      Will this muffler cause an emissions test failure?

      • This will not cause any emission test failures no.

      Helpful (0)

      I have a 2005 mustang and was wondering how do I install it??? Do I have to weld it??? Or what? Tia

      • The Flowmaster American Thunder Axle-Back Exhaust will simply clamp on to your exhaust. More details can be found in the install guide, linked below:

      Helpful (0)
      10 More Questions
      How can I hear the actual sound of the Flowmaster American Thunder Axle-Back Exhaust on the 2005 to 2009 Mustang V6? Is there a video to hear from Flowmaster? Thanks. 1 answer
      Does this exhaust have an annoying drone sound to it or does it sound good while driving 1 answer
      It says the exhaust includes a hanger, I have a 2007 mustang and Im just changing the one exhaust to this , will I still need the hanger kit ? 1 answer
      Will this fit a 2004 V6? 1 answer
      Will this fit on a stock 05 mustang without any other items for it? I mean can it just go right on after taking off the stick muffler just as easy as that?? 1 answer
      I notice a great decrease in my horse power when I installed this piece. I like the noise it makes but it accelerates slow. How can I get my horse power back? Should I buy another pieces instead? 1 answer
      So I have this for 8 years now and really wanna convert to dual and still keep my old one question can I buy just the other side (left side ) since I already have the right one thank you .. 1 answer
      If I instal the flow master exhaust on my 2005 v6, would I have to do a tune up for it?? Or what do I have to do? 1 answer
      How can I make this into a dual exhaust setup? Would an x-pipe work with this? 1 answer
      How well will this worth when i install long tube headers? 1 answer

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Muffler assembly
      • (1) Exhaust Hanger

      Tech Specs

      Axle-Back Exhaust Specifications
      Piping Material: Aluminized Steel Tip Material : Polished Stainless Steel
      Piping Size: 2.5" Tip Size: 3.5"
      Muffler Type: Chambered Fitment: 05-09 V6 Mustangs

      Will It Fit My Mustang

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