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

Item J100311
Market Price $518.99 You Save 12% ($61.04)
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$457.95 (kit)

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      Review & Installation Video

      I'm Ryan with, 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

      Product Information

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


      • 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


      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 -


      Customer Reviews (56)

      Write a Review

      Ratings Summary

      4.4 out of 5 overall rating from 56 customers

      Installation Time: Afternoon

      Installation Cost: $100-$250

      • January 05, 2020

        4 2008 Wrangler - RandyC Installation Time: Afternoon

        Great sound, very poor fit

        Installed in 2008 2 door jk. After reading about fitment issues we took it slow and measured several times with everything in place but loose. The exhaust as bent does not fit right. The tip is pointed to the drivers side at like a 45degree angle and the e haust hanger is stretched extremely tight. There us no way to rotate the tip to face down as the bend in pipe and hanger weld prevents it. I love the sound as i am a fan of flowmaster, but making one exhaust to fit 4 different models really makes a $500 feel cheap and poorly made. When i spend that much i dont want it to feel cheap and poorly made. Doubt i will buy another cat back system. I will buy muffler only and have a shop bend tube.

        Helpful (2)
      • December 24, 2019

        5 2011 Wrangler - macleaver Installation Time: Less than 1 Hour

        Easy Install

        Great sounding exhaust for the 3.8L. Hardest part was taking the old exhaust off, then assembling the new one was like a piece of cake. 2 Doors, make sure to leave and extra inch than what the instructions say as I had no issues with the hangers this way.

        Helpful (2)
      • December 08, 2019

        4 2017 Rubicon - NWJKUR Installation Time: Shop Install

        Good Tone, Too much drone

        The build quality of the exhaust is fantastic, very solid and nice welds. Love the high tuck design and really clears up some room under the Jeep. However with any high tuck exhaust comes drone. The exhaust itself sounds great, but it’s just one step under straight piped and the drone gets old quickly. I added a 12inch Vibrant resonator right after the “muffler” (not much of a muffler) and it’s perfect now. 0 drone, and an ever deeper tone to the exhaust. If you want something a little louder than stock, this is not for you.

        Helpful (1)
      • May 04, 2019

        4 2009 Wrangler - Maxxxxxxxxxxxxx Installation Time: Afternoon

        Sweet sounds

        This is a great upgrade makes my Jeep sound great and wasn't hard to install only thing that sucked is flow master was to cheep to give new rubber mounts

        Helpful (2)
      • April 14, 2019

        5 2018 Rubicon - NVAJEEPBRIGADE

        American thunder

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

        Helpful (1)
      • April 02, 2019

        3 2007 Wrangler - RVAJK Installation Time: Less than 1 Hour

        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.

        Helpful (3)
      • December 03, 2018

        5 2012 Wrangler - JonW Installation Time: Afternoon

        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.

        Helpful (6)
      • September 20, 2018

        4 2014 Rubicon - AlecC Installation Time: Less than 1 Hour

        Sounds great!

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

        Helpful (5)
      • August 14, 2018

        5 2008 Rubicon - AdamB Installation Time: Less than 1 Hour

        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.

        Helpful (7)
      • August 06, 2018

        5 2017 Wrangler - ArpadK Installation Time: Afternoon


        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

        Helpful (7)

      Questions & Answers (7 answers)

      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

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Inlet Pipe Assembly
      • (1) Muffler
      • (1) Over Axle Pipe
      • (1) Exit Pipe Assembly
      • (1) Clamp & Hanger Kit

      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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