---
product_id: 1329745
title: "Flowmaster 17421 American Thunder Axle-Back Exhaust Kit 2.5 Inch Aluminized Steel 4 Inch Polished 304 Stainless Steel Tips Compatible with 2005-2009 Ford Mustang 4.0L V6 Coupe or Convertible"
price: "C$50605"
currency: NIO
in_stock: true
reviews_count: 8
url: https://www.desertcart.ni/products/1329745-flowmaster-17421-american-thunder-axle-back-exhaust-kit-2-5
store_origin: NI
region: Nicaragua
---

# 4-inch polished 304 stainless steel tips Moderately aggressive exterior exhaust tone Mandrel bent 16-gauge aluminized steel tubing Flowmaster 17421 American Thunder Axle-Back Exhaust Kit 2.5 Inch Aluminized Steel 4 Inch Polished 304 Stainless Steel Tips Compatible with 2005-2009 Ford Mustang 4.0L V6 Coupe or Convertible

**Price:** C$50605
**Availability:** ✅ In Stock

## Summary

> 🔥 Unleash the Thunder: Elevate your Mustang’s roar and style!

## Quick Answers

- **What is this?** Flowmaster 17421 American Thunder Axle-Back Exhaust Kit 2.5 Inch Aluminized Steel 4 Inch Polished 304 Stainless Steel Tips Compatible with 2005-2009 Ford Mustang 4.0L V6 Coupe or Convertible
- **How much does it cost?** C$50605 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.ni](https://www.desertcart.ni/products/1329745-flowmaster-17421-american-thunder-axle-back-exhaust-kit-2-5)

## Best For

- Customers looking for quality international products

## Why This Product

- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Dyno-Tuned Sound:** Experience a perfectly balanced aggressive exhaust note that turns heads.
- • **Premium Stainless Tips:** Sleek 4-inch polished tips add a bold, refined finish to your Mustang.
- • **Complete Installation Kit:** Includes hangers and hardware for a hassle-free, professional fit.
- • **Precision Mandrel Bending:** Ensures optimal exhaust flow and durability for peak performance.
- • **Tailored for 2005-2009 Mustang V6:** Custom compatibility guarantees seamless integration and enhanced driving dynamics.

## Overview

The Flowmaster 17421 American Thunder Axle-Back Exhaust Kit features mandrel-bent 16-gauge aluminized steel tubing and polished 4-inch 304 stainless steel tips, delivering a moderately aggressive exhaust tone. Dyno-tuned for maximum performance, it includes all necessary hangers and hardware for easy installation, designed specifically for 2005-2009 Ford Mustang 4.0L V6 models.

## Description

Flow master 17421 Axle-back System - Single Rear Exit - American Thunder - Moderate Sound

Review: Absolutely A+. Breathed new life into my ride - Installation wasn't hard at all, getting the old muffler out was harder. Here's a quick guide, since I couldn't find any good videos on removing the factory. There are two hangers that support the factory muffler, as well as some sort of rubber band on the back. The hangers came out pretty easily (13mm bolts, ratchet worked with most of them but I needed a wrench for one just due to the position). The rubber band hanger thing wouldn't detach and wasn't really important anyway, so I just cut it off. Getting the muffler off of the car's exhaust pipe was the hardest part. There's a little nub that fits into a cut in the factory (and flowmaster) muffler. Douse the entire connection with as much WD-40 as you can find, then twist that sucker back and forth while pulling it forward and down. If all else fails, whack the connection with a hammer a couple times to loosen up the joint. Whack the ring on the connection a few times too, but mine was welded onto the factory muffler. Once the old rusty factory one is off, grab your shiny new Flowmaster, put the included clamp ring around the not-shiny end, and shove that thing over the factory pipe. Remember that nub- you'll have to fit the little cutout around it. Once it's all the way on, move the ring to right around the nub (Mine is maybe 5mm before the cutout for it) and tighten it down pretty much all the way. That's solid steel, so it'll hold up the muffler well enough so you dont have to hold up 15 pounds of steel while trying to bolt stuff on. Then slide the two muffler hangers around the pegs on the top (and just ignore the peg at the back, that's where the rubber thing would connect but it really doesnt matter) and start bolting it up. Make sure you've got the tip in the right spot before securing it down. Once everything is in place, get all that stuff nice and tight, start up your stang, and enjoy that beautiful sound. It'll smell like burning plastic for the next little while since there's some junk inside of it that might melt, no biggie. Review-wise, I absolutely love this muffler. Sounds amazing, but not loud. I honestly think it sounds better than a stock GT. It's not annoyingly loud, and at moderate radio volume I can't notice the exhaust at all, but when I hit the gas it sounds AWESOME. This is also the cheapest I can find it anywhere ($270 on AM and other sites, I got it for $220 on desertcart) so just buy this. The Pypes just makes a lawnmower sound, this is absolutely worth the extra money!
Review: nice but.... - sounds great...install was super easy....waaaaay overpriced for what it is

## Features

- Includes Hangers and Hardware for an Easy Installation
- Mandrel bent 16-gauge Aluminized Steel Tubing
- Moderately Aggressive Exterior Exhaust Tone
- Dyno Tuned for Maximum Performance
- 4.00-inch Polished Stainless Steel Tip

## Technical Specifications

| Specification | Value |
|---------------|-------|
| Manufacturer | Flowmaster |
| Brand | Flowmaster |
| Model | 17421 |
| Item Weight | 17.65 pounds |
| Product Dimensions | 20.1 x 12.5 x 10 inches |
| Item model number | 17421 |
| Is Discontinued By Manufacturer | No |
| Exterior | Painted |
| Manufacturer Part Number | 17421 |
| OEM Part Number | 17421 |

## Images

![Flowmaster 17421 American Thunder Axle-Back Exhaust Kit 2.5 Inch Aluminized Steel 4 Inch Polished 304 Stainless Steel Tips Compatible with 2005-2009 Ford Mustang 4.0L V6 Coupe or Convertible - Image 1](https://m.media-amazon.com/images/I/61uyBo1u9+L.jpg)
![Flowmaster 17421 American Thunder Axle-Back Exhaust Kit 2.5 Inch Aluminized Steel 4 Inch Polished 304 Stainless Steel Tips Compatible with 2005-2009 Ford Mustang 4.0L V6 Coupe or Convertible - Image 2](https://m.media-amazon.com/images/I/51WnOwY4VaL.jpg)
![Flowmaster 17421 American Thunder Axle-Back Exhaust Kit 2.5 Inch Aluminized Steel 4 Inch Polished 304 Stainless Steel Tips Compatible with 2005-2009 Ford Mustang 4.0L V6 Coupe or Convertible - Image 3](https://m.media-amazon.com/images/I/61KQFn4M+dL.jpg)
![Flowmaster 17421 American Thunder Axle-Back Exhaust Kit 2.5 Inch Aluminized Steel 4 Inch Polished 304 Stainless Steel Tips Compatible with 2005-2009 Ford Mustang 4.0L V6 Coupe or Convertible - Image 4](https://m.media-amazon.com/images/I/61a2pLdBp9L.jpg)

## Available Options

This product comes in different **Style** options.

## Questions & Answers

**Q: Is it compatible with my mustang 2005 v6?**
A: Yes it fits any 05-09 V6 Mustang

**Q: This exhaust system is two mufflers correct?  I only see one in the picture and obviously the system would require two per vehicle. Please clarify.**
A: Just one

**Q: Will this fit my 2005 Scion tC?**
A: It's made for the Mustang V6.  It would not fit your car.

**Q: Could this be converted for a 2015 camaro rs**
A: I believe the mounts are different, but you can check the Flowmaster website for compatibility.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Absolutely A+. Breathed new life into my ride
*by G***R on August 15, 2018*

Installation wasn't hard at all, getting the old muffler out was harder. Here's a quick guide, since I couldn't find any good videos on removing the factory. There are two hangers that support the factory muffler, as well as some sort of rubber band on the back. The hangers came out pretty easily (13mm bolts, ratchet worked with most of them but I needed a wrench for one just due to the position). The rubber band hanger thing wouldn't detach and wasn't really important anyway, so I just cut it off. Getting the muffler off of the car's exhaust pipe was the hardest part. There's a little nub that fits into a cut in the factory (and flowmaster) muffler. Douse the entire connection with as much WD-40 as you can find, then twist that sucker back and forth while pulling it forward and down. If all else fails, whack the connection with a hammer a couple times to loosen up the joint. Whack the ring on the connection a few times too, but mine was welded onto the factory muffler. Once the old rusty factory one is off, grab your shiny new Flowmaster, put the included clamp ring around the not-shiny end, and shove that thing over the factory pipe. Remember that nub- you'll have to fit the little cutout around it. Once it's all the way on, move the ring to right around the nub (Mine is maybe 5mm before the cutout for it) and tighten it down pretty much all the way. That's solid steel, so it'll hold up the muffler well enough so you dont have to hold up 15 pounds of steel while trying to bolt stuff on. Then slide the two muffler hangers around the pegs on the top (and just ignore the peg at the back, that's where the rubber thing would connect but it really doesnt matter) and start bolting it up. Make sure you've got the tip in the right spot before securing it down. Once everything is in place, get all that stuff nice and tight, start up your stang, and enjoy that beautiful sound. It'll smell like burning plastic for the next little while since there's some junk inside of it that might melt, no biggie. Review-wise, I absolutely love this muffler. Sounds amazing, but not loud. I honestly think it sounds better than a stock GT. It's not annoyingly loud, and at moderate radio volume I can't notice the exhaust at all, but when I hit the gas it sounds AWESOME. This is also the cheapest I can find it anywhere ($270 on AM and other sites, I got it for $220 on Amazon) so just buy this. The Pypes just makes a lawnmower sound, this is absolutely worth the extra money!

### ⭐⭐⭐⭐ nice but....
*by K***. on May 21, 2025*

sounds great...install was super easy....waaaaay overpriced for what it is

### ⭐⭐⭐⭐⭐ Easy Install, Great Sound, Definite Performance Improvement
*by D***E on November 17, 2010*

I bought this axel back system because I was never happy with the sound from my V6. I had previously tried a GT Take Off Muffler (an exhaust removed from a new GT) and while it sounded a little better than stock it was simply not good enough. I just fitted this Flowmaster in under 45 minutes and went for a 10 minute test drive. Yes it is that easy to install this on a 2007. The sound is great, much deeper than before, louder but not too obnoxious. No drone on the highway but a great sound everywhere else. I would highly recommend this exhaust. No it wont sound like a V8 but it certainly sounds more muscular as it should, and there is a definite performance improvement. Overall I am very happy with this purchase. I had considered going to true dual exhausts but in the end the cost just for an improved sound, didnt make sense. One last thing to mention, the exhaust has been on the car for a week and it sounds better than when it was first installed and there is a definite performance improvement. Flowmaster claim 10 HP and I can certainly believe that.

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*Product available on Desertcart Nicaragua*
*Store origin: NI*
*Last updated: 2026-03-07*