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Thermal R&D Cat-Back Exhaust (15-17 GT Fastback)

Item 403883
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      Video Review & Installation

      Hey, guys. Today, we're gonna be taking a look at and installing the Thermal R&D Cat-Back Exhaust for 2015 to 2017 GT Mustangs. This is gonna be a great option for someone who wants a high-quality cat-back that's loud but that has absolutely no raspy notes and no drone at all. This cat-back also has a wide range of volume, meaning that it's very quiet at idle and in the lower RPMs but it gets louder as the RPMs rise. And when it comes to loudness on a scale of one to five, with one being a quiet upgrade and five being a very loud upgrade, I'm gonna call this one a strong four out of five on the loudness meter. This cat-back has a lot of the same qualities that you see for more expensive cat-backs but it's more budget friendly. It costs about $950. It's made from 3-inch 304 stainless steel and has 4-1/2 inch polished tips on it. I'll call the install a two out of three wrenches in the difficulty meter and I'll show you how we got it on the car now. For this install, I used an electric ratchet, but you guys can use a normal ratchet, that'll work just fine. I used a 3/8 impact gun with a short extension, a shallow 13-millimeter, a deep 13-millimeter, and a deep 15-millimeter socket, as well as a mallet. We're gonna drop our stock cat-back as one big piece so we're gonna go ahead and loosen these clamps right here at the resonator. They are a 15-millimeter.Now we're gonna move back and we're gonna undo the two 13-millimeter bolts that are holding these hangers in place. We're gonna leave the hangers still clipped into the body but just undo the bolts. Now we're gonna move to the back hangers that are holding the muffler in place. There are two 13-millimeter bolts there. At this point, we're ready to drop our cat-back as one big piece. You guys might need a second set of hands to help you out here. You'll knock the cat-back out of the hangers on the body and then just push back on the resonator. So here we have our Thermal cat-back compared to our factory cat-back, you guys can see that the Thermal cat-back looks a little bit different. If we start at the front here, Thermal gives you two adapters and they do this so that you can bolt this cat-back up to your factory header and cat setup or you can eliminate the adapters and run a full three-inch exhaust setup instead. We are gonna install the cat-back with the adapters because we still have the factory headers and cats on the car. This is made from 3-inch 304 stainless steel so you have high-quality materials but you also have high-quality craftsmanship here as well. All of the welds on this cat-back look great and you guys can see that the tubing has a brushed finish to it, that leads us to our mid-pipe. The mid-pipe is a three-chambered muffler and Thermal does this so you have a loud cat-back but without any rasp at all. This is a tuned cat-back so you don't have uncontrolled noise and volume from the cat-back.We're gonna go down here to our mufflers. You guys can see these look very different than what you typically see with a cat-back muffler. These have Thermal's Helmholtz technology and they are straight-through mufflers, so the whole point here is to be loud with a tuned sound. So it's not gonna be loud just to be loud. You won't have any raspy notes and you also won't have any drone at all with this cat-back. That's a huge plus for you guys out there that drive your Mustangs a lot. And the entire system is finished with Thermal's 4-1/2 inch slant-cut tips. This does have a lifetime warranty on it as well. Now, at this point, we're gonna go ahead and get this cat-back installed in the car. All right, guys, so, at this point, we're gonna transfer the hangers over from our factory cat-back to the Thermal cat-back. You're just gonna wanna keep an eye on the orientation of them and make sure you're placing them in the correct place on the Thermal cat-back. So we'll go ahead and just pull these off. You guys might need some WD-40. When we pulled our stock cat-back, one of the clamps stayed on the resonator and one stayed on the car. This may have happened to you guys as well, it's not a big deal. What we need to do though is just pull this off now so we can go ahead and get our adapters installed. We're gonna pull this off and slide it back onto the car. So we're gonna slide our factory clamp into place. We're gonna push the other clamp back into place because that got a little loose.We're gonna grab our adapters and slide the adapter in on both sides. From here, I'm just gonna take a little mallet, I'm gonna knock these in a little bit. Okay, guys, we're ready for the resonator now. Just so you know, there are welds on one side of the resonator and that's the side that needs to be pointed up towards the bottom of the car. So we're going to install this with that facing up. We're also gonna put two band clamps on this before we install it. You wanna make sure, obviously, that the nut's facing down so you can tighten it once it's on the car. I also have two pole jacks here with me. These are gonna help me get the exhaust up and into place. I'm gonna get my clamps on and we're gonna go ahead and lift this up into place. So, at this point, I'm gonna use the pole jack to put the resonator up higher then I'm gonna use my mallet to go ahead and try to knock it into these clamps a little bit more. Okay, next, we're gonna install the driver side tailpipe. But before we do that, we're gonna slide our clamp into place. I am gonna position this so the bolts are on the differential side, just to give us more clearance. We'll this slide this on, then I'll grab the driver side tailpipe and get the hangers in place. All right, so we're gonna clip our hanger into the body of the car. All right, so now we're gonna line this tailpipe up with the end of the resonator and slide the clamp over. All right, we are gonna leave it loose because I wanna be able to adjust things if we need to, to keep everything straight. So I'm just gonna leave it like that, for now. At this point, we're gonna go ahead and get our two 13-millimeter bolts back in the rear bracket here.We're going to leave this bracket up here loose, for now, just to give us a little bit more flexibility in the system. Now, I'm gonna use the pole jack and get the tailpipe up in place so I can tighten this clamp up here. This needs to go up a little higher. I'm checking the alignment out the rear bumper because I wanna try to get it in position for the tip to be installed, that's where I need the exhaust to be. So I'm gonna rotate this clamp up just because I like the hardware to be away from the bottom of the exhaust. So I'll rotate it up and then I'm gonna go ahead and tighten this down. All right, so we're gonna throw our tip on this side. Once again, you'll need a clamp and you're gonna wanna make sure that the nut is facing down where you guys can tighten it. So I'm gonna slide the tip onto the exhaust pipe and I know it's not perfectly straight right now in the rear bumper but I'm just gonna go ahead and tighten the tip down anyway. Then after I get the other side installed, I'll go back through, make sure everything's straight and get the tip aligned properly. All right, so we're gonna do the exact same thing on this side. We're gonna slide our clamp onto our resonator and with the hardware on the diff side. Then I'm gonna grab the tailpipe and hook the tailpipe hangers into the body of the car. So, once again, we're gonna go ahead and get our rear hanger bolted down.All right, so now I'll take the pole jack and just take our tailpipe up a little bit higher before I tighten that clamp. All right, so now we're ready to tighten this clamp back here. Once again, I'm gonna rotate it up so my hardware is not hanging down below the exhaust and I'll tighten it. So now, I'll put our tip on. Once again, we'll take a band clamp, slide it on with the hardware facing down so we can tighten it, and slide it over the tailpipe. At this point, we only have a few things left to do. I'm gonna go through and tighten down all of our clamps. I'm gonna make sure I put those hanger bolts back in over the diff back there and then I'm gonna make sure that the exhaust is completely straight. If I need to, I'll loosen some clamps, straighten the tailpipes, and then go from there. All right, guys, that's gonna wrap up this review and install. Keep in mind that you can always check this cat-back out more online. I'm Stephanie. And for all things Mustang, keep it right here at

      Product Information

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


      • Cat-Back Exhaust
      • Cutting-Edge Thermal R&D Helmholtz Technology
      • Improves Horsepower up to 25 RWHP
      • Delivers Augmented Exhaust Tone
      • Made for High-Performance on Street and Track
      • Heavy-Duty 304 Stainless Steel Construction
      • Features Straight-Through Design
      • Sleek Polished Mufflers and Tips
      • Brushed Finished Tubing
      • Tubing Diameter: 3 Inches
      • Angle Tips: 4.5 Inches
      • Basic Installation
      • Lifetime Warranty
      • Fits All 2015-2017 Ford Mustang GT Fastback Models


      Improved Horsepower. The Thermal R&D Cat-Back Exhaust features cutting-edge Thermal R&D Helmholtz Technology that will effectively improve horsepower in your Ford Mustang GT Fastback by up to 25 RWHP. You’ll love the augmented exhaust tone and high-performance capacity that is perfect for driving your Mustang on the street or the track.

      Steel Construction. Heavy-duty 304 stainless steel is used to manufacture this exhaust kit, which features a straight-through design for improved exhaust flow. The 4.50-inch angle tips and mufflers have a sleek and polished finish. The brushed finish tubing has a 3-inch diameter.

      Basic Installation. Six specialized clamps are included in this Thermal R&D Cat-Back Exhaust to ensure a straightforward installation and proper alignment of the tip. If you plan on expanding on this build and want to run the system to performance headers, then you’ll love the included adapters that will facilitate this additional process.

      Lifetime Warranty. This exhaust comes with a limited lifetime warranty covering craftsmanship defects. Review the warranty information since some limitations may apply.

      Application. The Thermal R&D Cat-Back Exhaust is designed to fit all 2015-2017 Ford Mustang GT Fastback models.

      Fitment: 2015 2016 2017 Details

      Thermal R&D B906-C906

      CA Residents: WARNING: Cancer and Reproductive Harm -

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (2) Polished Mufflers
      • (2) 4.50-Inch Angle Cut Tips
      • (6) Specialized Clamps
      • Adapters

      Customer Reviews (21)

        Questions & Answers

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