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BBK Stainless Steel Varitune Offset/Offset Oval Muffler; 2.50-Inch (Universal Fitment)

Item 56243
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      Review & Installation Video

      Hey I’m Justin with and this is my brief breakdown of BBK’s Varitune muffler available for all later generation Mustangs. The Vari-tune is a fully tunable muffler allowing the owner to change his or her tone in a matter of minutes simply by adjusting the power valve here on the muffler itself. By opening and closing the valve you are essentially changing from a 3 chambered muffler and a single chambered muffler. This allows you to go from a relatively quiet exhaust setup to a loud, aggressive setup in a matter of minutes using nothing more than a simple wrench to adjust the power valve. To see how everything works BBK was nice enough to send a sample that has been cut-up to expose the inner workings of the muffler itself. As you can see with the power valve fully closed like it is now, the exhaust has to travel through all 3 chambers which is going to keep the sounds levels down considerably. However, as soon as you open up that power valve all the way, you’re essentially bypassing these first two chambers and it’s at that point the exhaust becomes much louder and you might pick up a few horsepower at the rear wheels thanks to the increased flow. If you’re not watching this vehicle currently on our site and you want to hear some sound clips of this muffler in action, just click on the link to do so. BBK does offer the exhaust in both aluminized steel and full-stainless, with a slight difference in price between the two. The exhaust does come with these 4” polished tips standard, but there are optional 4” black tip available just in case you wanted to switch up the look a little bit. If you have any questions about going with a Varitune setup for your ride, just get in touch with one of our Mustang experts, you can give them a call at 855 422 7439 or drop them an email at As always you can find the Varitune and other great products from BBK right here at, and if you want to see my overviews on these products in addition to other great products for your ride, just subscribe to our YouTube channel by clicking the link below or up in the corner.

      Product Information

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


      • BBK Varitune Muffler with "Adjustable Power Valve"
      • Change from a Three to One Chamber Exhaust for More Power and Sound
      • 8-10 Decibel Range Difference
      • Offset Inlet and Outlet Design
      • 2.5" Inlet/Outlet Diameter
      • Stainless Steel Construction
      • Sold Individually
      • Universal Fitment; Modifications Will Be Required


      Adjustable Sound. BBK's patented tunable Varitune performance mufflers allow you to change from a mellow three chamber exhaust sound to a rich throaty straight-through exhaust note with just a twist of a wrench, for a 8 to 10 decibel sound level difference!

      How It Works. BBK Varitune performance mufflers utilize an internal "Adjustable Power Valve." When in the closed position the valve blocks the exhaust flow, forcing it through all three chambers of the muffler for a classic mellow sound. When in the open position, the valve "uncorks" the exhaust flow, allowing it to take the path of least resistance, acting more like a straight-through muffler for a rich throaty exhaust note. This unique design is perfect for personalizing the power and sound levels of your Mustang to suit your own specific needs.

      Stainless Steel Construction.
      Manufactured using the highest quality heavy gauge Stainless Steel available, BBK Performance utilizes both robotic and hand welding to ensure the quality and durability of each of their mufflers. Modifications Required. This Muffler was designed to be used on mutliple applications, as it is not a direct fit replacement part. In order to install this Muffler properly on your vehicle, some modifications to the exhaust system will be required.

      Application. This BBK Varitune Muffler features a 2.5" inlet and outlet diameter in an offset configuration making it the perfect muffler for 1979 to 2004 Mustangs, including the LX, V6, GT, Bullitt, Mach 1 and 1994-1998 SVT Cobra models. Excludes 1999-2004 SVT Cobras with IRS.

      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

      MPN# 31015

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (11)

      Write a Review

      Ratings Summary

      4.6 out of 5 overall rating from 11 customers

      Installation Time: Afternoon

      Installation Cost: $100-$250

      • September 10, 2019

        2 1999 GT - JamesH Installation Time: Shop Install Installation Cost: 0-$100


        These are amazing, they look and sound great. Highly recommend

        Helpful (0)
      • January 14, 2019

        5 2002 GT - leann Installation Time: Less than 1 Hour


        I bought these mufflers to put on my 2002 mustang gt i used to have dynomax i have flowmasters but these bbk mufflers out do both of them if you want them loud open them wide open and they still sounds good the more you open them more muscle they sound they got iam not going any where else to buy muffles even the muffers shop owner had never heard of them or seen anything like it but there's one thing i didn't tell you about my mustang i have long tube headers gutted catalyst converters with illuminator if you have illuminator make sure they are on the front not back i didnt put my tail pipes back on because i love the rumble thats comes from underneath the car

        Helpful (4)
      • November 12, 2016

        5 2004 GT - shaker56 Installation Time: Less than 1 Hour

        good overall sound

        I have the Catback exhaust and thought it was a little to loud so I replaced the muffler with the Varitune mufflers they sound good they are not as deep as the Catback but they sound good I would recommend them to anyone that wants a muffler that can be adjusted to your sound

        Helpful (8)
      • September 02, 2016

        5 2003 V6 - Gargoyle

        Best for V6

        I own a 2003 V6 . I previously had a Flowmaster exhaust , while it was ok, something was lacking. I switched to high flow cats and the BBK Varitunes. After playing around with the settings on the Varitunes , I was able to get the exact sound I wanted, with a bonus of some added power. System was installed by professional shop. I highly recommend these mufflers !

        Helpful (9)
      • June 10, 2016

        5 1986 GT - jeff1986 Installation Time: Less than 1 Hour

        exhaust upgrade

        I really struggled with what muffler I wanted to upgrade to. I wanted something that had a good tone but did not sound like a truck. This is the muffler to have. With the varitune feature you can change these bad boys from a three chamber muffler for good tone but not to loud for daily driving to a single chamber unit that says come on lets see what you got. The change over is done with a bolt set up that screws in and out to open the unit up or close it down and takes less than 5 minutes. These mufflers have great tone and the quality and fit were awesome.

        Helpful (8)
      • March 21, 2016

        4 1996 Cobra - Jeff Installation Time: Afternoon

        Varitune mufflers

        Awesome exhaust and sound sweet unfortunately these universal mufflers don't have hangers. Besides that count be happier!

        Helpful (9)
      • October 21, 2014

        5 2003 GT - andrewbball21 Installation Time: Less than 1 Hour

        Best muffler you can buy!!!!

        With the decision of choosing the BBK Varitune Mufflers you are able to adjust the volume of your exhaust very quickly and with no hassle. These mufflers completely change the sound and even the overall feeling when driving your vehicle. Throughout the break in period of the mufflers, the sound continually got deeper and sounded more like a muscle car. I purchased these mufflers and couldn't be more blown away with the outcome. If you want to hear the true power of your engine and gain some horsepower while your at it, buy these mufflers and you will be very pleased with the result.

        Helpful (9)
      • September 26, 2014

        5 2007 V6 - Moberdorf302 Installation Time: Less than 1 Hour

        Great muffler. Modified to fit 2007 v6

        Bought this muffler three weeks ago for my 2007 mustang. I knew there would be a little modification to allow the exhaust pipe to fit properly. Took roughly an hour to cut weld and mount this new muffler. I left the first setting the quietest setting on for a fully week and let me tell you. It did not sound like a quiet setting! The cabin drone was not too bad more than stock but still quiet enough to not wear ear muffs. Within two days I was receiving complements and being asked questions about it. Massive head turner. After the first week I opened the exhaust up and was still quite impressed. There is a large difference between the sounds from clods to open. While it was open it still wasn't too loud inside but outside it was extremely loud. My friends hear me coming down the road. And from a few roads over. Overall extremely impressed with this product. Eventually will get a true dual and first thing will be to get another one of these and pop it on. No regrets.

        Helpful (8)
      • July 18, 2014

        5 1998 V6 - Stretch2248 Installation Time: Less than 1 Hour

        Bbk exhaust

        It will defiantly bring out the sound ur looking for even before the 2 week mark

        Helpful (22)
      • November 16, 2013

        5 2001 GT - ab01gt Installation Time: Shop Install

        Very happy with BBK Varitune mufflers!

        I had my initial review deleted because after about a 2 week break in period I have been much more impressed with these mufflers. At first they didn't seem loud enough but the volume and tone improved a bit as they broke in. The mufflers are about as loud as stock when the valves are closed; with them open, they are a little louder than the Magnaflow Street mufflers I previously had. I do a lot of highway driving and wanted a system that wouldn't have annoying drone, so I'll mention that there is a light drone around 2k rpm (valves open), but it isn't loud enough to be a bother. The exhaust sounds great when you get on it, but I do wish it was a little louder still with the valves open. Every couple weeks, I close the valves for a few days and then when I open them back up its like having new mufflers again. I would definitely recommend these for anyone who was to give their Mustang a great sound without being obnoxiously loud. These may be the perfect daily driver exhaust.

        Helpful (9)

      Questions & Answers (2 answers)

      2 Top Rated Questions

      Anyone have the measurements for this muffler? I currently have a flowmaster American thunder catback with 40 series muffs. Will these bbk varitunes fit into this system or will it need cutting and welding to fit in?

      • This BBK Varitune Muffler measures to 17.75" x 9.75" including the inlet and outlet. The Flowmaster Original 40 Series Offset Muffler is 19" x 9.75" including the inlet and outlet, so there would be a little extra cutting required due to the differences in length on the systems.

      Helpful (1)

      Will these mufflers fit my slp catbacks on my 01 GT without welding them in?

      • If the mufflers on your catback have the same length and pipe placement as the BBK Varitune Muffler - Stainless Steel 2.5 in. (79-04 All, Excludes 99-04 Cobra) then it will bolt up not problem, however if not you will have to do some modifications to make it work.

      Helpful (0)
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      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Muffler

      Tech Specs

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