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Flowmaster American Thunder Dual Exhaust System; Side/Rear Exit (14-18 5.3L Silverado 1500)

Item S104241
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      Video Review & Installation

      So the Flowmaster American Thunder dual exhaust system is one of the most popular dual exhaust systems available for the '14 to '18 5.3 liter-powered Silverado and Sierra, for a couple of reasons. Obviously, sound is most important and that number one reason as well. This is one of the deepest sounding exhausts currently available. Obviously, if you own a big American V8, you'll want that deep, throaty sound, and this certainly does deliver. Now, I'm happy to say, even though this is one of the deepest-sounding exhausts, it doesn't get crazy in terms of volume. I'm actually gonna give this a healthy three out of five on my loudness meter. I'd say this is perfect, it puts you right on the edge of that crazy amount of volume for a daily driver. It doesn't go overboard. And I'm happy to say that there's not a lot of drone inside the cab, that's all thanks to the 40 Series muffler that Flowmaster throws in with this kit. Now, besides sound, I'm really happy with the quality and the price of this system. Just below the $800 price point means this is one of the more affordable stainless dual exhaust systems. And if you've been shopping around and you're kind of looking for that perfect look, well, this is one of the only systems that gives you the choice of choosing between a split rare exit and a split side exit.I'm not actually sure that any other systems offer that currently, so that's a nice little bonus there. Now, besides the price, the quality is on par with some of the more expensive systems and I'm happy about that. This is made out of 409 stainless, which is factory grade stainless steel. So if you daily your truck, you see a lot of rain or snow, or you take your truck off-road, you don't have to worry about this thing rusting out on you anytime soon. I'm also very happy to say that the polished tips on here are stainless as well, so those will clean right up just fine. You don't gotta worry about the system looking ugly even if you do daily your truck like I just said. I'm also happy to say that the Flowmaster system installs relatively easily. This is a bolt-on kit. There's no cutting required. It's measured for your cabin bed length and they throw in the necessary extra pipes that you might need depending on your cabin bed length. So, again, you don't need to have any crazy power tools on hand in order to get this installed, you can definitely get it done in the driveway with hand tools. I am gonna give the install a modest two out of three wrenches on my difficulty meter. After all, we're working with some big heavy parts here and it might be a bit of a squeeze, but I promise you, you can definitely get this done at home in probably an hour or two.To install our new exhaust system, you'll need the following tools: a standard drive ratchet, a 15-millimeter deep socket, a 14-millimeter socket, a 13-millimeter socket, a 3/8 socket, a 14-millimeter wrench, and a 3/8 wrench. Optional but helpful tools include an air gun, an exhaust hanger puller tool, and spray lubricant. All right, so, obviously, before we install our new catback, we have to remove our factory exhaust, and we can actually do so quite easily. All you gotta do is loosen this clamp up here behind the wide pipe and the cat itself. To do that, you're gonna need a 13-millimeter socket. Once you've done so, all you gotta do is pop the factory exhaust hangers out of three rubber isolators, then you can actually remove the entire catback from the vehicle. I'll show you guys how to do that in just a moment but let's tackle this clamp first. So, once you got that clamp loosened, you wanna pull this rubber isolator. It's helpful to spray it down with some spray lubricant. It's also helpful to have an exhaust hanger tool. Now, once you've pulled that first rubber isolator, you're gonna tackle two behind the muffler here. All right, once you get to this last rubber isolator, you wanna take your time before you pull the exhaust from it. It's a little bit heavy so it's helpful to have a friend with you while you do this.What you wanna do is pull this last hanger from the rubber isolator, go ahead and let the over axle portion of your tailpipe rest on the axle. Once you've done that, go ahead and push the entire catback towards the rear of the truck, get the flex fitting over the cross member. You can actually remove the entire unit as one piece. So, we have our factory catback removed, it's a good idea to mock up your new system. I know I say that a lot, if you've watched some of our other exhaust videos, but, in this case, honestly, it's really important because you get to make a fun choice. Do you wanna go old school and dump straight out the back, or do you wanna go a little bit different and a little bit more creative maybe and dump out of the side? As you can see, we've got tons of pipes back here. Well, that's for making that choice there. Again, this is a split rear exit or split side exit. Either way, they do bolt on the same, so it all comes down to personal preference and what you think looks the coolest. Personally, I like the old school look, so we're gonna go dump it out of the back there. But, at any rate, couple of cool comparisons to point out here. Some nice things about the Flowmaster system, obviously, you get to reuse all your factory hanger locations. That's really nice because if you're doing this under the truck without a lift, it can get a little bit hairy under there. It's nice just to have things go on the way they came off, right?Other than that, other cool thing about the Flowmaster system, it's all made out of factory grade 409 stainless. That's really nice because as you can see, our truck has some miles on it but our exhaust from the factory still looks pretty good. You might get some surface corrosion on there, a little bit of rust here and there but you're not really gonna have to worry about this thing falling apart on you, which is obviously nice, especially if you take your truck out on the roads during the rain or snow or you take it off road. You don't have to worry about any pinhole leaks or any welds cracking for that matter. Those are where the similarities end. The differences that are really cool, obviously, you've got the super 40 Series muffler included in this kit. It's a hell of a lot smaller than our factory one, obviously, and we're ditching the factory resonator here on the tailpipe. That's what's gonna be responsible for all that volume and tone, so it's really no question why this thing sounds so good compared to the factory system. So let's go ahead and start throwing on our new system, shall we? So, obviously, the first step of our install is throwing on our mid-pipe and connecting it with our factory wide pipe. To do that, you're gonna tighten down that clamp we loosened earlier with that 13-millimeter socket. You only want to tighten it enough that it's held in place but still free. You wanna have a little bit of play in there. That way, you can make some adjustments as needed as we go along because we're not throwing this on piece by piece.Once you've got that all lined up, go ahead and throw this hanger into that first factory rubber isolator. All right, now, we can throw our muffler in place. Now, you're gonna wanna make sure you throw one of the large three-inch clamps here on the end of the mid pipe. That way, you can secure all this stuff later. You're gonna want the Flowmaster logo facing down towards the ground. And if you weren't sure which side goes where, well, obviously, this bright orange inlet is the one that you wanna throw on the mid pipe. Now, our new hangers are on our tailpipe, so there's not gonna be anything supporting this so it's helpful to have a jack or a friend hold this thing in place as you throw the tailpipes on. All right, now that we have our muffler in place that's being supported by this poll jack back here, we can start throwing on our tailpipes. We're gonna start with our passenger side tailpipe. You're gonna throw both of the hangers on the tailpipe into those original factory rubber isolators and you wanna make sure you're getting the tailpipe into the muffler as you do so. Now, before you do this, obviously, you wanna make sure you have a clamp on the outlet of the muffler. That way, you can tighten it down later. All right, now that our tailpipe is in place for the passenger side, we can throw on this little extension pipe and our exhaust tip, as well as one of these smaller clamps in the kit to tighten all this stuff together.Now, when you do this, again, you wanna leave everything loose because once we get the other side in place, we wanna make sure we have enough room to adjust everything. That way, both of our exhaust tips line up. All right, so our passenger side's all ready to go, now we gotta tackle our driver side. But, before we do that, we have to install this hanger for those new pipes. It's pretty straightforward. There's an oblong hole up here in the frame that you're gonna thread all this stuff through. You're gonna need one of these metal backing plates. You honestly don't need both because you already have a small plate on the one side. You're also gonna need this little bolt, this little nut here, as well as a flat washer and crush washer in the kit. And in order to tighten all this stuff down, you're gonna need a 14-millimeter socket and a 14-millimeter wrench. All right, now that our hanger is in place, we can finally install our driver side pipes. It's the same exact process as the passenger side. Go ahead and throw the main tube onto the end of the muffler. Again, make sure you're throwing clamps on all these pipes. Once you got this guy in place, it's just a matter of throwing on the extensions with the last hanger for that isolator we just threw up there. And then we can throw in our exhaust tips, line everything up and we can start tightening everything down. All right, now both of our tailpipes and our exhaust tips are in place, we get to do the finishing touches here before we're wrapped up. You're gonna tighten down all your clamps and it's best to work from front to back. That way, you can line everything up piece-by-piece as we go along. So we're starting up here in front of the cross member, we're gonna tighten down that original clamp that we loosened in the very beginning. You're gonna need your 13-millimeter socket for that. Once you've got that tightened down, you're gonna use a 15-millimeter deep socket for all the clamps you installed. And then finally, for the exhaust tips, we go over to SAE for some reason. We're gonna use a 3/8 socket for those guys. So once you've got your tips lined up, all those clamps tightened down and you're happy with where everything sits, that'll actually wrap up the install. That also wraps up my review of the Flowmaster American Thunder dual exhaust system, fitting your '14 to '18 5.3 liter-powered Silverado or Sierra. I'm Travis. Thanks for watching. Keep it right here at

      Product Information

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


      • Moderate to Loud Sound Level
      • Better Scavenging and Exhaust Flow for Increased Horsepower and Torque
      • Delta Flow™ Super 40 Series Muffler
      • Has 2.5 in. Mandrel Bent Stainless Steel Tubing
      • Features with 3.0 in. Polished Stainless Steel Exhaust Tips
      • Split Side or Dual Rear Exits
      • Bolt-On Installation
      • Designed for Double and Crew Cab Models
      • Not for Use with 2WD Crew Cab Models with 2-Piece Driveshaft
      • Fits 2014 to 2018 5.3L Chevy Silverado 1500 Models


      Unique Flowmaster Sound. The Flowmaster American Thunder Cat-Back Exhaust emits a unique and powerful exterior exhaust note but keeps the interior sound level down to within comfortable levels. Indeed, Flowmaster’s patented Delta Flow technology is able to adjust both the interior and exterior sound levels. As a result, you can enjoy a comfortable ride with reduced sound levels inside the cab, while still turning heads with an aggressive exterior growl.

      Boosts Overall Performance. Due to the Flowmaster’s Delta Flow technology, your truck is sure to experience improved scavenging. When matched with the system’s mandrel-bent tubing, the result is a much smoother exhaust flow. This then leads to improvements in horsepower, torque, throttle response, and even fuel efficiency.

      Premium Stainless Steel Construction. The American Thunder Cat-Back is constructed from premium stainless steel. This allows for both outstanding durability and longevity, as well as minimizing the need for frequent maintenance over time.

      Bolt-On Installation. The American Thunder Cat-Back Exhaust makes use of factory mounting holes and can be bolted on easily with basic hand tools. It also comes with the option of having a dual side or dual rear exit configuration. Flowmaster recommends welding all slip-fit connections for a more secure installation.

      Application. The Flowmaster American Thunder Cat-Back Exhaust with split side or rear exits is designed to fit 2014 to 2018 5.3L Chevy Silverado 1500 models equipped with Double or Crew Cabs. It’s not compatible with 2WD Crew Cab models with 2-piece driveshaft.

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      Fitment: 2014 2015 2016 2017 2018 Details

      Flowmaster 817669

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      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Inlet Pipe
      • (1) 6.5 ft. Bed Extension
      • (1) Muffler
      • (1) Tailpipe, Right
      • (1) Tailpipe, Left Front
      • (1) Tailpipe, Left Rear
      • (2) Side Exit Pipes (Right and Left)
      • (2) Rear Exit Pipes (Right and Left)
      • (2) Stainless Tips
      • Installation Hardware

      Customer Reviews (100+)

        Questions & Answers

        10 More Questions

        Will It Fit My Silverado 1500

        • 4.3L V6 - 14, 15, 16, 17
        • 5.3L V8 - 14, 15, 16, 17, 18

        Designed for Double & Crew Cab Models. It is not compatible on 2WD Crew Cab Models with 2-Piece Driveshaft.

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