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Flowmaster American Thunder Cat-Back Exhaust with Black Tips (18-23 3.6L Jeep Wrangler JL)

Item J126475-JL
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$905.95 (kit)

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      Video Review & Installation

      Hey, guys. So today I'm here with the Flowmaster American Thunder Cat-Back Exhaust System, fitting all 2018 and newer JL Wranglers with the 3.6-liter V6 engine. So if you're looking to liven up your JL, get a deeper exhaust note and a louder exhaust note, while also creating a more aggressive look out of the rear end of your Wrangler, this option by Flowmaster is a really good one to take a look at.So this is gonna free up a lot of that restriction that you were seeing with that factory exhaust system and it's going to increase your performance, as well as your MPG, while creating a very aggressive note out of your exhaust, while not being over the top and no interior noise. So as far as noise level goes I'm going to give this a four out of five on the loudness meter. This isn't gonna give you a whole ton of noise, but it is gonna be a lot more aggressive than some of the other options that I've seen before. So as far as Flowmaster goes, this is gonna be their second loudest exhaust system following the Outlaw. So this isn't gonna be for somebody who's looking for the loudest exhaust system, but this is definitely gonna be for somebody who wants to hear their exhaust system whenever they get on it.So as far as price goes, this is gonna be roughly $700, making this a more affordable option compared to other exhaust systems or other cat-back systems in the same configuration. And when I say that, you have a dual exhaust, single exhaust, and a high clearance exhaust. A lot of those lesser expensive options are usually gonna be for a single outlet or they're going to be for those high clearance options since there's not a lot going on there and they are gonna be a little bit more simplistic.So then on the other side you have those more expensive options that are usually going to be configured like this. However, they may have a different style muffler, a straight through style muffler instead of a baffled one like this that's gonna create a louder noise level or they may just have more pieces to the puzzle. Upfront they may have a resonator like your factory exhaust system, so it really comes down to what you're looking for out of your exhaust. I personally think this is gonna look really good mounted up underneath the Wrangler while also creating a very aggressive sound. And considering the fitment is very on point, I definitely thing that this is a great option to take a look at.So install is gonna be a very easy one out of three wrenches on the difficulty meter. If you do have a two-door, you will have to cut some of the exhaust system out. However, it is very simple. So speaking of the install, let's jump into that now.The tools that I used for my install were an impact wrench, PB Blaster, an exhaust hanger tool, a 10-inch extension, a 3/18-inch drive ratchet, a 13-millimeter ratcheting wrench, a marker, a 15-millimeter and 13-millimeter deep socket, and a 13-millimeter swivel socket.So what we're gonna do is start at our muffler. I'm gonna go ahead and take off our exhaust hangers. You're gonna need a 13-millimeter swivel socket and a 13-millimeter ratcheting wrench to do so. So I'm going to take a 13-millimeter swivel socket and a 10-inch extension as well as my ratchet, and we're gonna take off that top bolt.So you can also just use a standard 13-millimeter socket, but I find it a little bit easier to use a swivel if you have it just because it gives you a little bit more room to work with far as movement goes.So after that bolt is removed, we can take our 13-millimeter ratcheting wrench. You may be able to fit a socket in here as well if you need to, but I find a ratcheting wrench is a little bit more low profile. And we can go ahead and remove the side bolt. So after the one side is unattached, we can move to the other side and do the same thing. So I'm just gonna do the same thing on the other side.So I'd like to mention right now, I do have the muffler supported by a pole jack just to make sure that it stays in place while I loosen up this clamp. So you're gonna grab a 15-millimeter deep socket, and we're gonna go ahead and loosen up our muffler clamp.So now we can move our pole jack out of the way or whatever is supporting your muffler. And since everything is disconnected and loosened, we can go ahead and wiggle this off.So what we're gonna do next is move a little bit father back to behind the axle and we're going to remove our cat-back piping from our exhaust hanger here, from our frame. So I'm gonna use a little bit of PB Blaster just to lube it up, make it easier to pop out.Then we can grab an exhaust hanger tool and we can go ahead and remove that. With that removed from the hanger, we can move up to the front and loosen up our cat-back piping clamp. So now with a 13-millimeter socket we can loosen up our clamp here. And once that's loose, make sure you have a hand on your exhaust. That will come right off.So at this point, you're gonna have to just wiggle it out. So before I go ahead and bolt this up, I did wanna show you guys a little bit of a side by side comparison next to your factory exhaust and show you the benefits that you're getting out of this new one that you won't see with the factory. So right off the bat you can tell that you are getting a very small muffler with this. It's gonna be an incredible downsize, saving you a little bit of weight, freeing up a lot of restriction, and it's also just gonna look a lot more attractive mounted up underneath your Wrangler than your factory exhaust is. So speaking of that muffler, this is going to be a chambered muffler that's built to create a very aggressive exhaust note out of your Wrangler and it's also gonna create a very aggressive look. It's not big and bulky like your factory muffler and it also has these really aggressive dual tips on here. So this is gonna be made of 409 stainless steel. The four-inch dual tips are gonna be made of a premium 304 stainless steel and it also has a really nice black ceramic powder coat on it, again, to achieve that aggressive look that you may be looking to get out of your Wrangler, but it's also going to protect that stainless underneath. Now you do see here that unlike on our factory exhaust system this has a second resonator or a second muffler up at the top there. This one does not, and it's also gonna be a little bit longer. Now that's because it is a for a four-door as well as a two-door. So I will show you guys in a minute that we are going to cut off most of this exhaust piping and size it down to what's suitable for a two-door. So speaking of that, let's go ahead and install our new exhaust.So if you have a four-door, you can bolt on your exhaust as is. However, if you have a two-door like we do, you will have to measure out 21 and a half inches on your cat-back piping and you're gonna have to cut that off in order to accommodate for that shorter length. So what we're gonna do is go ahead and cut that off.So now that we're ready to install our exhaust, we're gonna take that pipe that we just cut or the longer portion with the flanged end, take our factory clamp, and attach it to our cat piping. So we are gonna be reusing our factory clamp. It seemed like it was a little bit easier to put it on our cat piping before. And we're going to get around both of the pipes. I'm just going to tighten this up. We still wanna leave it a little bit loose so we can adjust it. However, we do need to keep this in place while we attach the rest of our exhaust.I'm just gonna tighten this up a little bit. We want that adjustment but we don't want it flopping around. Right. So now we can grab our middle pipe that's gonna go over our axle and attach that to our cat-back piping.Now with our provided clamp we're gonna go ahead and put that on. And we do wanna make sure that this lines up with our hanger. So we're gonna go ahead and install our hanger right here. Making sure that that is where it's supposed to be. And then we can go ahead and snug this up. Again, we're not gonna tighten everything down because we do need that adjustment once we put our muffler on. And I'm gonna take a 15-millimeter socket, a deep socket, and we're gonna just snug that up.Now we can grab our muffler and transfer over our exhaust hangers. What we can do now is just spray our hanger with a little bit of lubricant so we can remove it a little bit easier. And we can take our exhaust hanger tool and separate our hanger from our factory exhaust. I find it a lot easier to do this while it's off the Jeep. You don't have a lot of space up in the air while it's still mounted up. And it's just easier overall on the JL, at least, to transfer over these while they're off the Wrangler.So now with our factory hangers, we can install them on our new exhaust, making sure that they're on the correct side, oriented in the correct way. And then I don't like how there's now a little knob here already kind of welded on but they do give us hanger keepers, so you can just put that on the end there to make sure that the hanger does not slip off.So with our clamp in place we can grab our muffler. Go ahead and mount that up. So after that's most of the way in place I'm gonna grab my pole jack just to keep this where it is while we bolt everything up. So with your muffler supported, we can grab our hanger and bolt that up.Now I'm just reinstalling the factory bottom bolt just to keep this secured to our frame. We can do the same thing on the other side. So now that we have our muffler supported, we can just go ahead and reinstall the rest of our hanger. Just reinstalling that factory hardware.And we can tighten it down with our 13-millimeter ratcheting wrench and our 13- millimeter socket. Now with that big muffler out of the way, you'll have a whole ton of room so you won't need that extension. Now I can do the same thing on the other side.So now with a 15-millimeter socket we can go ahead and tighten down our aftermarket exhaust clamps, making sure that they're well positioned over our flange here. Now we can continue back. Same 15-millimeter deep socket to tighten up our middle clamp. And then we can move to our last clamp, which is going to be tightened down with our 13-millimeter socket.So your last step is just to make sure that you have your hanger retainer on your last hanger. Once that's on there, you are all set to go.So that's gonna wrap it up for my review and install. Make sure you like and subscribe. And for more videos like this, keep it right here at

      Product Information

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

      Features & Specs

      • Produces an Aggressive Exhaust Sound
      • Enhances Exhaust Flow for Improved Performance
      • Chambered Muffler Design
      • 409S Stainless Steel, 2.50-Inch Mandrel-Bent Tubing
      • Black Painted Muffler Finish
      • Dual Out Rear (DOR)
      • Includes Black Ceramic-Coated 4-Inch 304 Stainless Steel Exhaust Tips
      • Easy, Bolt-On Installation
      • Fits 2018-2023 3.6L Jeep Wrangler JL Models


      Supremely Aggressive Sound. The Flowmaster American Thunder Axle-Back Exhaust gives you and your Jeep significantly noticeable confidence with its thundering exhaust note and equally powerful driving performance. Additionally, the resonant tuning chambers innovatively produce moderate interior sound with an overall improved quality and level of control.

      Superior Performance. This American Thunder Cat-Back Exhaust features a chambered muffler design with superior capabilities in scavenging and refocusing of the exhaust gases. Its Power Chamber and Delta Flow technologies expertly regulate precise phase shifts to maximize power gains. The resulting increase in horsepower and torque provide the Jeep with significantly improved overall vehicle dynamics, both on and off the road.

      Built to Last. Flowmaster equipped its American Thunder exhaust system with long-lasting durability. It is constructed from premium, 409 stainless steel with mandrel-bent tubing, fortified with a black painted finish. The fierce exterior is further reinforced with a pair of exhaust tips – suitably made from 304 stainless steel and coated with black ceramic finish. This entire exhaust system is designed to handle harsh driving conditions, including the constant attacks from the corrosive exhaust gases and thermal stress from catalytic activities.

      Direct Installation. This American Thunder Cat-Back System is designed for a bolt-on installation. It is seamlessly compatible with the JL’s factory hangers and can be installed in around 1 hour with light-to-moderate mechanical skills.

      Application. This Flowmaster American Thunder Cat-Back Exhaust with Black Tips is designed to fit 2018-2023 3.6L Jeep Wrangler JL models.



      Flowmaster 817819

      CA Residents: WARNING: Cancer and Reproductive Harm -

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Resonator
      • (1) Front Pipe
      • (1) Over-Axle Pipe
      • (1) Muffler
      • (3) 2-1/2-Inch Stainless Band Clamps
      • (3) 7/16-Inch Hanger Keepers

      Customer Reviews (70)

        Questions & Answers

        10 More Questions

        Will It Fit My Wrangler

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        • JL Wrangler 2 Door - 18, 19, 20, 21, 22, 23
        • JL Wrangler 4 Door - 18, 19, 20, 21, 22, 23