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Flowmaster American Thunder Axle-Back Exhaust with Polished Tip (21-23 Bronco, Excluding Raptor)

Item FB15128
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$428.95 (kit)

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      Video Review & Installation

      Jake: Jake here for ExtremeTerrain. And today, I'm taking a look at this Flowmaster American Thunder Axle-Back Exhaust with the Polished Tip, fitting 2021 and newer Broncos, excluding the Raptor. If you find that your Bronco is lacking in the exhaust department but you aren't in business of upsetting all your neighbors or your own eardrums, then this American Thunder system from Flowmaster might just be the right setup for you. It gives you some extra rumble without going overboard, and it keeps that clean OEM look with a smaller tip that tucks up onto the bumper.Volume-wise, we're gonna give this one a three out of five on our loudness meter. Certainly noticeable change versus stock, but not as loud or as unhinged as a more straight-through system. When someone mentions the name Flowmaster, I'd be willing to bet that most of us can conjure up exactly the type of exhaust note that the company is famous for, a verbally aggressive V8 rumble. And while you're obviously not gonna get that out of either of the Broncos engines, you do get a really nice deep tone that makes either the 2.3 or the 2.7 sound pretty darn good.Now, as you heard from the clips at the beginning of the video, this one does have a little bit of volume to it, though it's not quite wake the neighbor's level of noxious. It's a big difference over stock, but not so much that you're gonna disrupt the whole neighborhood on cold mornings. That said, you are gonna get quite a bit more volume inside the cabinet as well. And that sound is due in no small part to the muffler here.Now, this is an axle-back system, so this is only gonna replace your factory rear muffler. And in place of your original one, you get one of Flowmaster's 60 Series mufflers. So, this is gonna provide that deep rich tone and keep things in check sound-wise inside the cabin as well. But roll down the windows, drop the top, and you'll get to hear that nice growl coming out of the tailpipe.This muffler is also packed with Flowmaster's patented Delta Flow technology. And that's gonna help combat drone. This is a chambered muffler, and inside, you've got triangular or delta-shaped baffles that separate sound waves and cause them to collide at very specific angles, later on, to help cancel out unwanted frequencies.Now, according Flowmaster, this also creates a negative pressure within the muffler, which is gonna help pull exhaust gases throughout the back, thus relieving some back pressure in the system, gives you a little bit of added performance as well. Now, the tip on the end is also a nice little slash-cut chrome deal and it's pretty subtle, all things considered. It is a bit of a turndown, as you can see. It tucks right up under the bumper in a similar place to your factory tip, so if you are doing some off-roading, it's not really gonna change the clearance out back, meaning that your departure angle is intact here as well.The system is constructed from 409-grade stainless steel. It's all mandrel-bent and 2.5 inches in diameter. And that 409 stainless is gonna provide you some good resistance to corrosion and rust. Now, it won't be quite as good as 304 stainless, but it is still a nice level of protection for your ride. It saves you a bit of money versus a 304 setup as well. But to help offset that, this is also coated in a high temp black finish. So, this is gonna be even more resistant to damage and the elements. It's gonna make for a clean-look tube once it's installed.Pricing for this system is gonna come in at just about $500, and that makes it one of the least expensive options out there for the Bronco. Now, again, you're saving a bit of money over a T304 stainless setup. But if what you're really after is a good quality system with a nice sound profile, this is gonna be an excellent choice that's gonna fit any build budget.Installation gets a one out of three on our difficulty meter, and should take you about an hour to complete. Since this is just an axle-back, the whole process is a little bit simpler than a full cat-back, and should take you a little less time as well. Now, this is gonna use your factory exhaust hanger locations. Now, all the hardware that you need is included, and it doesn't require you to make any modifications. The hangers that they give you in the kit just bolt right up. You don't have to drill any holes or anything like that. So, it's pretty easy to get done right at home in your driveway. So, just take your old one off and then bolt this one up. And to show you exactly how to get that done, let's head on out to the install bay now.Man: For this install, you will need an impact, ratchets, extension, 10, 13, 14, 15, and 18-millimeter sockets, 10 and 14-millimeter wrenches, a hanger removal tool, and some penetrating lubricant. What's up, guys? Today we're gonna be installing a new exhaust on our Bronco, so let's get started. So, our first step is gonna be to loosen up our clamp to our muffler inlet pipe. And to do that, we're gonna use our 15-millimeter socket on our impact.Next, we can go ahead and remove our hangers from our isolators using our hanger removal tool. And it's always a good idea to spray a little penetrating lubricant into where your hangers are, just to make sure they slide out easily. Let me get that one loose, and then we'll move over to our other ones.Maybe you wanna grab hold of your muffler because it'll be ready to swing after this.This other one all the way out, go ahead and get this other one all the way out. And go ahead and wiggle our muffler out, and set our factory system aside. So, for this particular system, we're gonna be replacing this rear hanger here from the factory with the supplied aftermarket one. So, we're gonna need to remove it. And these do have captured welded nuts on the bracket, so we will have to unbolt our bumper just to access the bolts through the back of the frame here. So, we're not gonna actually take it off all the way, we're just gonna unbolt it to give us some room to access those.So first, we're gonna remove our bottom two 18-millimeter bolts on each side using our 18-millimeter socket on our impact. Now, we'll go ahead and remove the other two on the other side. Tow hook is held in by a little clip, but you can just pull it right out.So next, we can come to the outside of our frame horns here and remove this inner 13-millimeter bolt on each side using our 13-millimeter socket on our impact. So next, we can come to the backside of our bumper here next door frame rail and remove this upper inside 13-millimeter bolt using our 13-millimeter socket on our impact. Then we'll go ahead and remove the same bolt on the other side.Okay. So, now that we have our bumper unbolted, we've got it supported on pole jacks. But if you have a buddy or jack stands, you can do the same thing at home. So, we've just gone ahead and pulled the bumper back, and there are these 2 access holes to access the 10-millimeter bolts that are holding our factory isolator hanger in. So, we'll go ahead and use our 10-millimeter socket on our ratchet. Just get up in there and remove these two bolts.Now there are holes on the bottom of your frame, so don't worry so much about dropping the bolts. You do have easy access to them. First one out, and then the second one. Now, the second one you don't really have to pull out, but if it falls out, that's okay. So, now we're gonna get ready to install our new supplied hangers. And for that, we're gonna make sure our passenger-side hanger is curved ground and facing back towards the center of the vehicle, like so. And then we're gonna take our factory hardware, slide it through our second bolt hole in, go ahead and attach our supplied lock nut loosely for now.And then our other bolt is gonna go in the all...the one all the way closest to your hanger bend point. So, we'll go ahead and install that lock nut as well. So, now we're gonna go ahead and tighten down our lock nuts just a little bit more before we install them. So, I'm gonna use my 13-millimeter socket on my impact and a 10-millimeter wrench. Go ahead and run that down a little bit.Do the same thing for the other side. Now, we can go ahead and slot our bracket bolt back through our slots here, move those into position. Now, you can sneak a 10-millimeter wrench up in one of these access holes here. Then we'll go ahead and use our 13-millimeter socket, tighten these down, get that snug, do the same thing for this one.Now, we'll go ahead and do the same thing for the other side. So, now we're gonna use supplied hardware and a 14-millimeter shallow socket, as well as a small extension, fish the mounting bolts for this side up through into our holes. So, once we have our first one in, we'll get our bracket in place. Again, we're gonna go second hole here, closest to the bend in your hanger. And then we'll use our supplied flat washer, lock washer, and nut. We'll get this one loosely in place for now.Now, we can go ahead and get our other one installed. Fish this one through. Same thing, flat washer, lock washer, and nut, get that hand-tight. And then we'll go ahead and grab our 14-millimeter wrench, as well as our 14-millimeter socket and extension on our ratchet to go ahead and tighten these down.So, now we can go ahead and reattach our bumper, and we'll start by hand-tightening our 13-millimeter bolts here on the outside of our bracket to our frame. Get this one hand-tight, as well as the one on the other side.Now, we can go ahead and thread in our lower 18-millimeter mounting bolts. And then we'll do the same thing on the other side, as well as attach our tow hook. Now we can put our push clip back in the middle section of our tow hook, push that back up into place to hold it, and go ahead threading our two 18-millimeter bolts on this side. Now, we can go ahead and tighten our outer bolt down using our 13-millimeter socket on our impact. And go ahead and do the same thing for the other side.Now, we can go ahead and tighten down our bottom bolts using our 18-millimeter socket and our impact. And you can repeat this on the other side. So, this particular system we're installing does not reuse this factory hanger isolator point. So, you do have the option of removing it with two 10-millimeter bolts right here. For demonstration purposes, we are actually gonna leave it in place, but if you wish to take it off at home, you can without affecting anything.So, now that we have our hangers in place, it's time to go ahead in with our new system. And we'll start by lining up our muffler inlet tube with our over axle section. I can get that set in, and get this isolator in and push that into place. Now, for your driver-side isolator, it's best for this system to go ahead and install it onto both hangers at the same time. Get that pushed in as far as you can. Get everything lined up and square. Now we can go ahead and tighten down our clamp using our 15-millimeter socket on our impact.All right, guys, that about wraps up our review and install of our Flowmaster American Thunder Axle-Back Exhaust with Polished Tip, for your '21 to current Bronco, excluding Raptor. Thanks for watching. And as always, for everything Bronco, keep it right here at

      Product Information

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

      Features & Specs

      • Axle-Back Exhaust System
      • Excessive Exhaust Noise
      • Incremental Speed Additions
      • Flow-Inducing 3-Inch Inlet and Outlet
      • Scratchproof Stainless Assembly
      • Limited Lifetime Warranty
      • Basic Installation
      • Fits All 2021-2023 Ford Bronco, Excluding Raptor Models


      Excessive Exhaust Noise. Are you not satisfied with the casual sound of your stock exhaust? Swap it out for the more aggressive Flowmaster American Thunder Axle-Back Exhaust with Polished Tip which offers an overtly loud exhaust roar that is sure to get everyone's attention.

      Incremental Speed Additions. The Flowmaster American Thunder Axle-Back Exhaust provides slight speed gains thanks to the ameliorated exhaust tubing which skips the catalytic converters and promotes quicker exhaust discharge.

      Scratchproof Stainless Assembly. The Flowmaster American Thunder Axle-Back Exhaust uses heat-resistant 304 stainless steel metal tubes that are checked for their sturdiness and quality to ensure that the tubing doesn't break or crack during installation or even after years of use.

      Warranty. This product comes with a limited lifetime manufacturer warranty that covers any manufacturer defects or damages prior to installation. Some limitations may apply to this warranty.

      Installation. This product does not require professional installation and would take roughly 1 hour to mount.

      Application. The Flowmaster American Thunder Axle-Back Exhaust with Polished Tip fits all 2021-2023 Ford Bronco, Excluding Raptor Models.


      • 2021 Ford Bronco
      • 2022 Ford Bronco
      • 2023 Ford Bronco

      Flowmaster 818121

      CA Residents: WARNING: Cancer and Reproductive Harm -

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Axle-Back Exhaust Assembly
      • Mounting Implements

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        Questions & Answers

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