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Flowmaster American Thunder Cat-Back Exhaust; Stainless Steel (99-04 Cobra)

Item 18448
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      Product Information

      Features, Description, Reviews, Specs & Installation


      • Aggressive Flowmaster Sound
      • 40 Series Mufflers
      • 3" Polished Stainless Steel Tips
      • Mandrel-Bent Tubing
      • 409 Stainless Steel Construction
      • Fits 1999-2004 SVT Cobra Mustangs


      Flowmaster Sound. Give your SVT Cobra that unmistakeable Flowmaster sound with a nice power boost by installing a American Thunder catback Exhaust system. Featuring mandrel bent tubing this Flowmaster system will improve exhaust flow for an increase in power, and the included Super 40 Series Mufflers will improve your exhausts sound for a deeper throatier muscle car exhaust note.

      Quality Construction. Constructed from mandrel bent 2.5" 409 stainless steel tubing for it's corrosion resistant properties the Flowmaster American Thunder Cat-Back features their 40 Series chambered mufflers with massive 3.0" diameter OEM style polished stainless steel tips for great muscle car looks and sound.

      Application. This stainless steel Flowmaster American Thunder Cat-Back exhaust system is specifically designed to fit the 1999 to 2004 SVT Cobra Mustangs with Independent Rear Suspension (IRS) for impressive looks and great sound.

      Fitment: 1999 2001 2003 2004 Details

      MPN# 817248

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (13)

      Write a Review

      Ratings Summary

      4.9 out of 5 overall rating from 13 customers

      Installation Time: Afternoon

      Installation Cost: $100-$250

      • October 28, 2018

        5 2003 Cobra - Kaysn Installation Time: Afternoon

        2nd Cobra with this exhaust, it's my favorite

        My 01 cobra came with the flowmaster thunder cat-back, so it was my first choice when I got my 03. Borla Stingers sound really good, but I personally prefer the slightly calmer sound of the flowmasters, and they are not as bothering to the neighbors. Definitely a great choice for a street vehicle to rumble when your foot is pressing, but docile when rolling along. Fair priced and much more appealing visually. Throaty sound without lots of popping and backfire on idle-down.

        Helpful (3)
      • February 26, 2018

        5 1999 Cobra - DevinD Installation Time: Less than 1 Hour

        Paired with a BBK x pipe

        I am really happy with the sound from this cat back. I cannot image having a louder kit.

        Helpful (3)
      • November 15, 2017

        5 1999 Cobra - NormanJahy Installation Time: Shop Install Installation Cost: $100-$250

        Sounds like a Cobra

        Exhaust sounds really good not too loud sounds good while idling, just enough to be noticed, it fit really well on my 99 Cobra and looks good.

        Helpful (5)
      • September 24, 2017

        5 1999 Cobra - ZachR Installation Time: Less than 1 Hour

        Great Exhaust Note!

        Gave my mustang that clean classic muscle car sound. Sound difference is definitely noticeable. Doesn't sound muffled or restricted. Has a nice open and throaty sound to it. I would recommend changing out your factory H-Pipe with this exhaust set up. Gave it better sound and also gave it a lot more pep when I got rid of the factory H-Pipe. Fitment was alright. Had to pull some of the exhaust hangers into the right position, not hard to do.

        Helpful (3)
      • May 18, 2016

        5 2003 Cobra - Chris Installation Time: Less than 1 Hour

        Great sounding exhaust!

        I was pleased the way they packaged the product as well as the quality. The flowmasters bolted right on and was an easy install ( I did mine on my lift) one cannot beat the sound of the flowmasters in my opinion all around easy fit great sound and great product!

        Helpful (6)
      • August 06, 2014

        5 2003 Cobra - Will Installation Time: Afternoon

        Its Flowmaster

        Replaced a 3" mac cat back off my 03 cobra with this and the sound and look are big improvement. Had to take the differential weight off due to passenger pipe hitting it but have not noticed any difference in driveline vibrations so I guess its ok, so -1 star for that.

        Helpful (5)
      • May 23, 2014

        5 1999 Cobra - 99MDCobra Installation Time: Afternoon

        Aggressive but not Overbearing

        I was looking for a little deeper sound, without annoying the neighbors (well, maybe a little). This catback provided what I was looking for. A little deeper sound to make it a little more like the Cobra it is, without it being too annoying for a car I drive on a regular basis. Maybe it'll help with the "Is that even a real Cobra?" I get for having a '99... Install wasn't too bad, the bolt spacing on the connection to the cats didn't have as much tolerance as I would have liked. I also had one hanger on the passenger side that was kind of stubborn to get up into, but in the end I was able to get everything lined up well. I'm a novice so take that into account, as my minor troubles may have just been chalked up to inexperience. I also have a new appreciation for the IRS this car has, as there was no up and over the axle to worry with. I'm happy with the result and got the sound I was looking for.

        Helpful (4)
      • May 02, 2014

        5 2001 Cobra - SteveM Installation Time: Shop Install Installation Cost: 0-$100

        Great sound!

        Installed on a 2001 cobra, sounds REALLY good. would recommend this product to any mustang owner. there is nothing like the sound of the 2 chamber flowmaster, gets your head turning!!

        Helpful (3)
      • August 26, 2013

        5 2004 Cobra - DebbieK3 Installation Time: Afternoon

        Awesome product!

        This was a great install. The sound was amazing! We were happy with the quality of the product. To top it off, we received a rebate from Flowmasters. This Cobra roars to life with our new pipes! We love it!

        Helpful (4)
      • July 24, 2013

        5 2003 Cobra - LexLuger Installation Time: Afternoon

        American Thunder

        All in all the product is great. I selected afternoon for install time based on whether or not you have a lift. I did it in my driveway with jackstands and it took the better part of an afternoon. Farthest bolt to the passenger side off the header is a doosie. But if you only ordered the cat back this won't be a problem for you. I installed this cat back with a Magnaflow carted tru-x pipe. NY compliant. Once that bolt was free the rest was fitting it in and leveling it out to tighten it up. I would recommend this to anyone who wants to hear the true beauty of owning a piece of American Muscle. 2003 Mineral Grey Vert Cobra

        Helpful (5)

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      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (2) Muffler assemblies
      • (2) Over axle pipes
      • (2) Exhaust Tips
      • (2) Clamps

      Tech Specs

      Cat-Back Exhaust Specifications
      Piping Material: 409 Stainless Steel Tip Material : Polished Stainless Steel
      Piping Size: 2.5" Tip Size: 3.0"
      Muffler Type: Chambered Fitment: 1999-2004 SVT Cobra Mustangs

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