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Flowmaster American Thunder Cat-Back Exhaust w/ Muffler Relocate (07-18 Jeep Wrangler JK)

ExtremeTerrain no longer carries the Flowmaster American Thunder Cat-Back Exhaust w/ Muffler Relocate (07-18 Jeep Wrangler JK). Please check out 2007-2018 JK Jeep Wrangler Cat-Back Exhaust for an updated selection.

Features, Video & Details

  • Cat-Back System
  • 409 Stainless Steel
  • Polished Finish
  • Made in the USA
  • Moderate to Aggressive Tone
  • 2.5 Inch Mandrel-Bent Tubing
  • Increased Off-Road Ground Clearance
  • Laminar Flow Super HP-2 Muffler
  • Limited Lifetime Warranty
  • Fits 2007-2018 JK Wranglers

Review & Installation Video

Review & Install Video

I'm Ryan with ExtremeTerrain.com, and this is my review of the Flowmaster American Thunder Catback exhaust system with muffler relocation, fitting all 2007 or 2016 Wranglers. This system will fit both two-door and four-door JKs. You should be taking a look at this exhaust system if you're looking for a little bit more sound out of your JK. This system will provide a lower and a louder exhaust sound. And something I really like about this Catback system over a lot of the axle-back systems that are available on the market is that this will completely relocate the muffler up and out of the way of rocks and other trail hazards. So if you've damaged your factory system and you're looking for a replacement, or you just want that lower, louder exhaust note, this is a good system to take a look at. Flowmaster built this out of 409 stainless, which is a quality stainless steel, but it's not going to quite give you the same corrosion resistance as a 304 stainless. So if you live in an area where they use a lot of salt on the road in the winter, like we do, you might still end up with some corrosion or surface rust with a system like this. All of the tubing is two and a half inch mandrel bent tubing, so you won't have any restriction on the bends, and the whole system is finished off with this nice polish tip. The heart of this system is the laminar flow Super HP-2 muffler. This gives you all of the flow and the sound of the HP-2 muffler in this compact square case, which is nice, because, like we said before, this tucks the muffler up out of the way of the trail hazards so it's not going to get damaged. When you take the system out of the box, you can tell that it is well-built and well-designed, even if the welds on the muffler leave a little bit to be desired, at least visually. Nice thing about this system is that Flowmaster backs you with a limited warranty. You can install this system at home in your driveway. Just keep in mind that the same system is sold for both four-door and two-door JKs, so if you're installing it on a two-door, you will have some cutting to do. The install instructions tell you exactly where to cut and how much. However, after we made that cut, we found that they told us to take off a little bit too much. We also had to do some additional trimming that wasn't in the installation instructions to get our system to fit right. So if you're not comfortable doing that type of cutting and fitting, I would recommend that you take the Jeep to an exhaust shop to have them install the system. If you do decide to install this system yourself, there are a couple things to keep in mind. As with any exhaust system installation, the install time will vary greatly depending on how rusty your stock system is. I would definitely recommend spraying all of the stock clamps and bolts with a good penetrating oil well before you get started. That will definitely speed things up. And those of you who have done exhaust systems in the past will know that the rubber exhaust hangers can be a little bit tricky. I would also recommend lubricating those and having a pry bar handy to pop them loose. This is a high-clearance exhaust system, so it tucks everything up out of the way, and clearance is a little bit tight in some spots. One spot in particular, where the new tubing runs between the sway bar and the rear cross member, is particularly tight. We were able to get our system adjusted so it didn't hit either the cross member or the sway bar, but it took some patience. With the additional trimming and the fine tuning, the entire installation should take about two hours. Once we got this system installed and out on the road, I have to say I really liked the way it sounded. It's definitely a lower exhaust note, and you get a little bit more volume, but you don't get a drone in the cab, which is really nice. We even got a little bit of popping and gurgling during engine braking with our stick shift. This system doesn't just sound good, it's also functional. It tucks everything up out of the way of trail obstacles and rocks. I have to say I do like the way it sounds and the way it functions. But I would have like to see it fit a little bit better right out of the box, especially for a system at this price point. Now there are exhaust systems that we offer that are more expensive, and they don't relocate the muffler, so I would say this is a really good value once you get it installed. So if you're looking for an exhaust system that will give you a lower and louder exhaust note, and tuck all the exhaust components up out of the way of trail obstacles, I would say this is a good choice, even if the install was a little bit challenging. That's my review of the Flowmaster American Thunder Catback exhaust system with muffler relocate, fitting all 2007 and 2016 JKs that you can find right here at ExtremeTerrain.com.

Construction. Flowmaster's American Thunder Cat-back exhaust system is constructed out of 409 stainless steel for lasting durability. This American made system features a 2.5 inch round, mandrel bent tubing for smooth, unrestricted airflow. Combined with Flowmaster's Patented Laminar Flow Muffler, this system will give your JK a throaty and aggressive tone. This system improves your JK's ground clearance by relocating the muffler up and out of the way of rocks and trail hazards. Experience the trails while enjoying your rig's new sound!

Application. Flowmaster protects their stainless steel systems with a limited lifetime warranty. This system fits 2007-2018 Jeep Wrangler JK Models.

Fitment: 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 Details

MPN# 817674

CA Residents: WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov

What's in the Box
  • (1) Inlet Pipe Assembly
  • (1) Muffler
  • (1) Over Axle Pipe
  • (1) Exit Pipe Assembly
  • (1) Clamp & Hanger Kit
Installation Info
Tech Specs
Will it fit my Wrangler?
  • JK Rubicon 2 Door - 07, 08, 09, 10, 11, 12, 13, 14, 15, 16, 17, 18
  • JK Rubicon 4 Door - 07, 08, 09, 10, 11, 12, 13, 14, 15, 16, 17, 18
  • JK Wrangler 2 Door - 07, 08, 09, 10, 11, 12, 13, 14, 15, 16, 17, 18
  • JK Wrangler 4 Door - 07, 08, 09, 10, 11, 12, 13, 14, 15, 16, 17, 18

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Questions & Answers (7)

5 Top Rated Questions

I reall like this system for my 2016 Jeep Wrangler jk but my question is will pass inspection without the catalytic converter

  • The Flowmaster American Thunder Cat Back Exhaust will install after the stock cat, allowing you to retain all emissions equipment and pass inspection.

Helpful (2)

Will this fit a 2015 jk 4door with 3.5” lift?

  • Yes, the Flowmaster American Thunder Cat-Back Exhaust w/ Muffler Relocate will be compatible with a 2015 jk 4 door with 3.5” lift. If you have an exhaust spacer installed you will need to keep it when this exhaust is installed.

Helpful (0)

Will this exhaust install EASILY, with the BBK long tube headers and high flow cat package. I will be installing by myself in a driveway and I can’t run into too many problems after o remove the old manifolds, cat, and exhaust. Thank you

  • We have this as two notches out of three in terms of the difficulty level of the installation. Light to Moderate mechanical skill will be required. We offer the installation guide on this product page, I would suggest to look into that to see what kind of install you will be getting yourself into.

Helpful (0)

Will this work with a teraflex 2.5 lift with spacers?

  • Yes, the Flowmaster American Thunder Cat-Back Exhaust w/ Muffler Relocate will be compatible with your lift.

Helpful (0)

Will this fit my 17 JKU? Other exhausts are listed with 2door or 4door... This one isn't.

  • The Flowmaster American Thunder Cat-Back Exhaust w/ Muffler Relocate will fit all 2007-2018 Jeep Wrangler JK models, both two door and four door.

Helpful (0)
Post Your Question
2 More Questions
Is it a loud obnoxious sound when you have the top off? 1 answer
Will this fit a 2017 Rubicon? 1 answer

Recommended For You

Customer Reviews (52) Write a Review

Overall Rating 4.4

out of 5 stars

Installation Time:Afternoon

Installation Cost:$100-$250

  • Exhaust Note 4.403846 4.4
  • Fit & Finish 4.307693 4.3
  • Bang For Your Buck 4.326923 4.3



  • 5/5

    April 14, 2019

    American thunder

    Awesome product and fast delivery. I recommend this product and also extreme terrain has a wonderful customer service.

    NVAJEEPBRIGADE

    Year: 2018Submodel: Rubicon

    Helpful (0)

  • 3/5

    Installation Time: Less than 1 Hour

    April 02, 2019

    Well-made but sound required more work

    Installation went fine - fit is tight, but is perfect with no trimming on the 4-door. Some have complained about weak clamps, but I thought they were fine - plenty beefy and held up well to an impact wrench. Maybe they have updated since other reviews - the muffler in my system was painted black - still stainless, but not the same finish as in the picture. On first start, it sounded really good - louder than I expected based on views of many videos, but not completely obnoxious...but it went downhill from there. Horrible drone at various RPMs including 1500-1900 which is where I spend a lot of time. I contemplated replacing with a stock muffler, but opted for a resonator (Flowmaster 15150S, not presently sold by XT) that per Holley is made for the HP-2 which is what the JK American Thunder includes. I cut a piece out of the straight portion of the over-axle pipe and inserted the resonator with a couple of heavy clamps from local auto parts store - Holley states it can be installed before or after the muffler and this approach allows me to pick either option - I went with after. Drone is now non-existent, and I'm left with a milder, rumbling idle and a reasonable mild-moderate tone on acceleration. Would I do it again? No - had I known it would cost $600 with the resonator being necessary to make things acceptable, I'd have likely opted to replace the rusted out stock muffler with a new stock muffler. That said, I'm pleased with the end result. Even with the resonator (very small profile) it's still a high-tuck system, it is a solid build and I do like the sound better than stock. Just not $600 better. My ratings are for the cat back only - with the resonator I would up the loudness and exhaust note to 4 stars each. Note - don't waste time trying to wrench the bolts off of your old setup - a metal cutting wheel on a mini-grinder makes the full removal a 20 minute job - cut the nut off the rear clamp, and since you can't reach the nut on the front clamp, I just cut the band. Hangers are fairly easily removed with PB and a medium pry bar and steady pressure...just find the right angle to get leverage.

    RVAJK

    Year: 2007Submodel: Wrangler

    Helpful (0)

  • 5/5

    Installation Time: Afternoon

    December 03, 2018

    Great product

    As most everyone has mentioned, the stock muffler was tough to remove. My Jeep was a Florida swamp/mud/hurricane Jeep until last month. You can imagine how bad the stock muffler was "welded" together from the salt, sand, and Everglades mud. Install went relatively smooth. As was said on here, remove your skid plate. I only removed three bolts and just swung it out of the way. Once installed, I torqued all the fittings, fired it up, and couldn't be happier. It almost sounds "manly" now.

    JonW

    Year: 2012Submodel: Wrangler

    Helpful (4)

  • 4/5

    Installation Time: Less than 1 Hour

    September 20, 2018

    Sounds great!

    Very easy install, sounds amazing, adds more attitude to the measly pentastar

    AlecC

    Year: 2014Submodel: Rubicon

    Helpful (4)

  • 5/5

    Installation Time: Less than 1 Hour

    August 14, 2018

    Great sound, easy install

    I bought a Jeep that had a straight pipe (no muffler). As you could imagine, it was loud and unrefined. Put the Flowmaster on and is has a great deep sound. No rice burner sound. Install was easy. Heard this one was a bit hard to install but didn’t experience that. Just keep clamps loose until fit is right.

    AdamB

    Year: 2008Submodel: Rubicon

    Helpful (5)

  • 5/5

    Installation Time: Afternoon

    August 06, 2018

    Greatest

    Fast awesome easy good quality sounds great would recommend for a throaty killer tough sound for your jeep tucks away nicely for off road protection

    ArpadK

    Year: 2017Submodel: Wrangler

    Helpful (6)

  • 4/5

    Installation Time: Afternoon

    August 04, 2018

    Great Exhaust

    Great sound and great product. Spray a generous amount of WD40 before you start anything. Rusted bolts made a 1 hour install a 3-hour install.

    SpencerB

    Year: 2013Submodel: Wrangler

    Helpful (5)

  • 4/5

    Installation Time: Afternoon

    June 28, 2018

    Installed on 2018 JKU with 3.5" Lift

    I actually installed this twice. First install was at stock height and it took about 4 hours to get the stock exhaust off and install this one. I had issues with the exhaust tip vibrating on the frame. It is an extremely tight fit around the rear sway bar. to make it work at stock height I had to cut 1/2" off the longest pipe in the kit. About a week later I installed a 3.5" lift with the rough country exhaust spacers. After installing the spacers I had to cut another 2" off the long pipe (1" at each end). The exhaust was very loud at stock height. After the 3.5" lift it seems quieter and sounds good. I gave it 4 stars because of the need to cut at stock height (I understand the need to cut after installing the spacers). Cutting was easy for me but not all people have the access to the extra tools needed to cut.

    BrettR

    Year: 2018Submodel: Wrangler

    Helpful (5)

  • 5/5

    Installation Time: Afternoon

    May 16, 2018

    Great product

    Super easy to get on the only hard part is removing the old one which took a few hours and some blood and sweat. After it was all said and done it sounds great and I would say it looks better but you cant really see it at all!!

    JonathanR

    Year: 2008Submodel: Rubicon

    Helpful (6)

  • 5/5

    Installation Time: Afternoon

    May 14, 2018

    Great exhaust

    Great exhaust very easy to install and sounds great. Took a little over an hour to finish took more time to take off old exhaust then to place the new one on. Would recommend if you want something easy and that has great sound

    CristianO

    Year: 2016Submodel: Wrangler

    Helpful (5)

  • 5/5

    May 04, 2018

    Exhaust American thunder

    Was looking for a exhaust with a deep tone and to be a little louder. It dose that perfectly, many a little louder than I was looking for. Over all I’m am loving it.

    Joec

    Year: 2007Submodel: Wrangler

    Helpful (5)

  • 4/5

    Installation Time: Afternoon

    April 22, 2018

    JK Exhaust

    Obviously if you're going wheeling on any rocks, the stock system gets in the way and you're constantly beating up that muffler and other components. This system gets it up and out of the way very well. On my 3.6-L this did have a slight ricer sound to it with the stock intake before replacing that. DON'T expect this to make your 3.6-L sound ANY WHERE near what a V-8 would sound like with an aftermarket exhaust. After all its just a V-6 and will still sound like a V-6, just with attitude now. If you're getting rid of your stock exhaust, forget taking out the bolts and such like the directions tell you. Just cut that stuff out of there. It will save you so much time. It does fit TIGHT going over the rear sway bar, but it DOES NOT rattle like you would think. It is quite loud, louder than i would've thought watching videos on this system. So if you don't want anything too loud, this might not be the one for you. It will take an hour or two to install, depending on how hard you work at taking your stock system off, like i said i just cut mine off since i wasn't going to use it anymore. and ALL the bolts were seized.

    DavidV

    Year: 2013Submodel: Wrangler

    Helpful (8)

  • 3/5

    Installation Time: Less than 1 Hour

    April 08, 2018

    Fit well with trimming but very loud

    Installed on 18jku. Fit very well after trimming 1.25 inches off the longest- resting against spring and sway bar before trimming. It’s much louder than what I expected but i’m hoping it will mellow out after a few hundred miles. 3 stars because of poor out of the box fit.

    JackH

    Year: 2018Submodel: Rubicon

    Helpful (7)

  • 5/5

    Installation Time: Less than 1 Hour

    March 19, 2018

    Awesome

    Very easy to install. Sounds deeper than stock. Replaced the muffler and the resonator. I was afraid it would sound like a 4 banger Civic but it doesn't.

    SamuelL

    Year: 2017Submodel: Wrangler

    Helpful (7)

  • 4/5

    Installation Time: Afternoon

    March 13, 2018

    Not too shabby

    Love the sound it makes. Pain to install since my stock exhaust was completely rusted on.

    BroganR

    Year: 2013Submodel: Wrangler

    Helpful (6)

  • 5/5

    Installation Time: Less than 1 Hour

    February 20, 2018

    Muffler is Amazing

    Got the product in less than 3 days. Boxed very well and no visual damage to the inside or outside of the box. Install was only about 20 minutes. Do not confuse that with the pulling of the the old muffler. Just the install. Sounds deep and growling like I wanted. I could not be anymore satisfied. Thank you exteme terrain for the deal and Flowmaster for the awesomeness attached to my Jeep.

    camvasey

    Year: 2017Submodel: Rubicon

    Helpful (6)

  • 4/5

    Installation Time: Afternoon

    February 13, 2018

    2014 Jeep 2door

    I installed this alone no lift or ramps and stock suspension so needless to say it was cramped still only took me about 3 hours for all of it. Tools that where very handy where air tools cutoff wheel, impact etc as long as you are some what mechanically inclined you get manage this install. Just make sure to measure over and over just like another review on here I actually had to cut 20” off the over axle piece and about 2.5” off the section that is before the muffler inlet (2 door). Sounds good for sure!

    ZaneD

    Year: 2014Submodel: Wrangler

    Helpful (9)

  • 5/5

    Installation Time: Afternoon

    January 12, 2018

    Great sound, quality product

    Sleek and shiny. Give your JK some serious oomph and volume. Nice upgrade

    EricS

    Year: 2010Submodel: Wrangler

    Helpful (7)

  • 5/5

    Installation Time: Less than 1 Hour

    December 13, 2017

    Easy Peasy...

    I got the Flowmaster quickly, and it was super easy to install. The biggest pain in the butt was taking the old stock muffler off. This system sounds great, and it feels a little more responsive. I highly recommend it.

    DavidR

    Year: 2010Submodel: Wrangler

    Helpful (7)

  • 5/5

    Installation Time: Shop Install

    Installation Cost: $100-$250

    November 25, 2017

    Different Animal

    After doing as much research as possible, I decided on this Flowmaster cat back exhaust to replace my ill-fitting Gibson side-swept cat back exhaust. Although I really did like the sound of the Gibson, this bad boy sounds pretty darn good! Makes my square peg even more of a surprise with the cold-air intake, performance throttle body, and ported manifold that I had installed previously. Don't underestimate that Wrangler that seems to be rumbling right next to you (muahahaha!!!)

    Bobzgirl

    Year: 2012Submodel: Wrangler

    Helpful (7)

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