WIN $5,000 For Your Mustang! Enter Now
Talk to a Mustang Expert
1-888-332-7930
Mon-Thu 8:30a-11p, Fri-Sun 8:30a-9p

Free Shipping - Get it by Dec. 24th available on most items - Details

Flowmaster 40 Series Offset Muffler - Stainless Steel 2.5 in. (79-04 All, Excludes 99-04 Cobra)

Market Price $101.37 You Save 12% ($11.67)

$89.70 (each)

FREE Shipping
  • Item 18433
  • MPN# 8042543

In Stock Ships same business day. Choose options to add to cart

Features & Details

  • Signature Flowmaster Sound
  • Original Two Chamber Technology
  • Offset Inlet and Outlet Design
  • 2.5" Inlet/Outlet Diameter
  • 409s Stainless Steel Construction
  • Sold Individually
That Flowmaster Sound. Improve your Mustangs exhaust flow for an increase in horsepower and a deeper throatier exhaust note with a set of Flowmaster 40 Series Mufflers for a truly classic muscle car sound.

Superior Design. The Flowmaster 40 Series Mufflers are MIG welded from durable 16 gauge 409s stainless steel for durability and value. The 40 series mufflers use Flowmasters original two chamber design to increase power and sound. And each muffler is embossed with the "Flowmaster" name so you know it is the real article.

Application. The 40 Series Muffler's outer case measures 4" x 9.75" x 13", and features a 2.5" diameter inlet and outlet in an offset configuration. This is the perfect muffler for the 1979 to 2004 Mustangs. Excludes 1999-2004 SVT Cobra.

Fitment: 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Details

What's in the Box
  • (1) Muffler
Installation Info
Tech Specs
40 Series Delta Flow versus 40 Series Original versus Super Flow 44 Series
  • Minimizes interior resonance
  • Aggressive exterior tone
  • Two Chambered Muffler
  • Made of Aluminized Steel
  • No minimization of interior resonance
  • Aggressive tone inside and out
  • Two Chambered Muffler
  • Made of Aluminized Steel
  • Delta Flow technology minimizes interior resonance
  • Aggressive deep powerful tone
  • Two Chambered Muffler
  • Made of Black Aluminized Steel
Will it fit my Mustang?
  • Bullitt - 01
  • Foxbody - 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93
  • Mach 1 - 03, 04
  • V6 - 94, 95, 96, 97, 98, 99, 00, 01, 02, 03, 04
  • Cobra - 94, 95, 96, 97, 98
  • GT - 94, 95, 96, 97, 98, 99, 00, 01, 02, 03, 04

Most Helpful Reviews

4/5
SS 40 Series

The only complaint I have is the mufflers don't have the hanger welded to it like the magnaflos had on the side closest to the rear axle. Other then the hanger missing its the best sounding muffler out ...

Read More
Helpful (1)

5/5
FLOWS !

Best option for your stock muffelr replacement, not too loud, nice low rumble, perfect, sounds great under the V6.

Helpful (1)

Overall Rating 4.8 out of 5 stars
Read All 16 Reviews

Customer Photos (2) Submit Your Photo

View All 2 Photos

You Might Also Like

6 Questions / 6 Answers

Ask a Question

Want the stainless steel flowmaster 40's. Are both sides the same? Are the flowmaster 40 mufflers for my 1989 mustang gt the same for both sides or is there a left and right muffler? I need the stainless 2.5". Thanks, Bruce

BA1964

  • Yes! The offset by offset can work on either Side! I hope this answers your question.

    JayM99

    Good Answer (0) (0)

Answer This Question I need this answered (0) (0)

does this product come with the exhuast tips?

luisc787

Answer This Question I need this answered (0) (0)

Will these fit my stock 02 V6 mustang?

Beckam

  • Yes, the Flowmaster 40 Series Offset Muffler - Stainless Steel 2.5 in. (79-04 All, Excludes 99-04 Cobra) will be able to fit a stock 2002 V6 Mustang.

    KevinD92

    Good Answer (0) (0)

Question Resolved

does the muffler have a hanger bracket on the rear of it like the factory muffler does

wink

  • The Flowmaster 40 Series Offset Muffler - Stainless Steel 2.5 in. (79-04 All, Excludes 99-04 Cobra) does not include a hanger bracket on the rear. Those will be able to reuse the factory hanger bracket.

    KevinD92

    Good Answer (0) (0)

Question Resolved

I currently own a '94 Cobra and would like to utilize the Flowmaster 40 series mufflers. Flowmaster no longer offers this muffler (instead they offer the 44 series muffler) in a full cat back exhaust set up. If I purchase two 40 series mufflers in 2.5in, the 2.5in Stainless Tailpipes (Part #20114), and the the 2.5in Flow Tube kit (Part #20109), will my muffler shop be able to build me a complete catback with these parts? Thank you!

94CobraDMV

  • Unfortunately, it would be difficult to say if your particular muffler shop could perform this modification, as it depends on the capabilities of the shop.

    AMJEFF

    Good Answer (0) (0)

Question Resolved

Can this fit on a stock exhaust, can I just take out the muffler and just put the flowmaster one in?

Noble117

  • Depending on the length of your stock muffler and the location of the inlet and outlet, this could be a direct replacement with the correctly sized clamps. If your stock muffler is shorter than the Flowmaster 40 Series Offset Muffler, additional cutting would be required.

    AMJEFF

    Good Answer (0) (0)

Question Resolved

More Products You Might Like

Customer Reviews (16) Write a Review

Overall Rating 4.8

out of 5 stars

Installation Time:Weekend

Installation Cost:$100-$250

  • Loudness / Volume 4.533333 4.5
  • Exhaust Note 4.733333 4.7
  • Fit & Finish 4.6 4.6
  • Bang For Your Buck 4.733333 4.7



  • 4/5

    May 17, 2013

    SS 40 Series

    The only complaint I have is the mufflers don't have the hanger welded to it like the magnaflos had on the side closest to the rear axle. Other then the hanger missing its the best sounding muffler out there.

    kwmiked04

    Year: 2004 Submodel: GT shelton CT

    Helpful (1) (0)

  • 4/5

    Installation Time: Less than 1 Hour

    December 24, 2015

    Great Sounding Muffler

    If U want that Classic Mustang Sound Original 40 series Flowmasters are they way to go...I had the Super 44 and let me tell u don't waist your time on a Fox Body Original 40 series is the way to go...and they look great under the car!!

    MustangMain

    Year: 1993 Submodel: GT Memphis, TN

    Helpful (1) (0)

  • 5/5

    Installation Time: Afternoon

    October 22, 2015

    Flowmaster exhaust kit

    Exactly what I wanted! My 1994 gt had a brand new exhaust on it when removed but it was all custom bent and looked TERRIBLE. This kit goes excellent with a bbk x pipe. I would recommend this to anyone and it bolt right in with no fabrication necessary. Looks more than professional when complete and sounds awesome! FANTASTIC PRODUCT! I would definitely buy this again if I bought another car

    Foxracer5824

    Year: 1994 Submodel: GT Petersburg, MI

    Helpful (1) (0)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: $100-$250

    August 09, 2015

    Nothing beats it in a 5.0

    True 2 chamber 5.0 sound. Fast shipping and great price.

    JCD

    Year: 1988 Submodel: GT Richmond, Va

    Helpful (1) (0)

  • 5/5

    Installation Time: Shop Install

    March 13, 2015

    Flowmaster 40 series stainless mufflers

    These mufflers are great! It's amazing how just changing out the stock mufflers can make my 4.6 sound so mean! They look great and have a nice classic, deep muscle car rumble.

    MaxPower

    Year: 2001 Submodel: GT Lakeland, FL

    Helpful (1) (0)

  • 5/5

    Installation Time: Afternoon

    October 18, 2013

    Awesome

    Installed these on my gt and sound amazing. I had them welded in bc clamps and adapters are a pain. Welding is the way to go !

    Jb02gt

    Year: 2002 Submodel: GT New York ny

    Helpful (1) (0)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: $100-$250

    November 08, 2012

    Awesome

    I've spent countless hours looking up exhausts and mufflers online! When I finally made my decision I choose the flowmaster 40 series mufflers in stainless steel. And let me tell u I couldn't be more happier! The sound is amazing! The stainless steel finish looks good too! I highly recommend this product to anyone who wants there car to come alive! Thanks AM!

    JayM99

    Year: 1999 Submodel: GT Whittier, CA, USA

    Helpful (1) (0)

  • 5/5

    Installation Time: Afternoon

    September 21, 2012

    Awesome!

    Very pleased with my purchase. Way more aggressive sound and note than stock muffler. Flows much better also. Definitely recommend for anyone looking to make their 99-04 v6 more aggressive sounding.

    Caesarion

    Year: 1999 Submodel: V6 Michigan, USA

    Helpful (1) (0)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    August 06, 2012

    FLOWS !

    Best option for your stock muffelr replacement, not too loud, nice low rumble, perfect, sounds great under the V6.

    iSayWhtSheFeels

    Year: 2000 Submodel: V6 Indianapolis, IN, USA

    Helpful (1) (0)

  • 5/5

    Installation Time: Afternoon

    August 27, 2015

    Hard to beat the sound on a 5.0 !

    Great fit, quick shipping, and a great price for a classic muffler! These sound amazing on the foxbody mustang.

    92gt

    Year: 1992 Submodel: GT mi

    Helpful (0) (1)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: 0-$100

    April 18, 2014

    Perfect muffler!!

    This muffler is awesome. It makes your v6 sound much deeper and more aggressive. Not like those mufflers that will make your care sound like a ricer, this makes your v6 sound like a v8!

    2004v6mustang

    Year: 2004 Submodel: V6 Goodman, MO 64843, USA

    Helpful (0) (1)

  • 4/5

    Installation Time: Shop Install

    Installation Cost: $100-$250

    June 27, 2014

    Good Product

    Mustang has louder tone and note to it. Notice improvement!

    Lt535

    Year: 2004 Submodel: GT Big Stone Gap, VA 24219, USA

    Helpful (0) (1)

  • 5/5

    Installation Time: Less than 1 Hour

    October 30, 2016

    Loud

    Tell all mustang drivers to put this on the stang.

    Rundown

    Year: 1994 Submodel: GT

    Helpful (0) (0)

  • 5/5

    July 17, 2016

    Just what i expected

    Combined these with just a off-road h pipe no cat oem headers oem cam. Sounds great. gets complements all the time. Shipped fast easy fit.

    Sn95guy

    Year: 1994 Submodel: GT

    Helpful (0) (0)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: $100-$250

    May 28, 2016

    Flowmaster 40's on a 1993 Mustang GT

    Love these mufflers! Great aggressive tone. Installed these with the Flowmaster 2.5" exhaust pipes, Pypes 2.5" flow tubes, and BBK Catted H-Pipe (all purchased here from American Muscle) on our 1993 Mustang GT to replace the aging (and rusted) custom catted H-Pipe, MAC exhaust pipes, and Dynomax mufflers. At idle, these Flowmaster 40 mufflers sound more hollow and a little more aggressive than the Dynomax ones we had on there. Getting up to speed in 2nd and 3rd really makes this car sing now! Cruising in 5th sounds great but no major drone. Would highly recommend these! Not too raspy....perfect for that classic 5.0 Flowmaster sound!

    smldbowen

    Year: 1993 Submodel: GT

    Helpful (0) (0)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: $100-$250

    May 23, 2014

    killer sounds, defanetly a head turner

    drivin down the road i love that i can turn heads my giving my car the gas, the deep sound just fits the car great and im very happy with it

    mikesil44

    Year: 2002 Submodel: V6 RI

    Helpful (0) (0)

Related Mustang Categories