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Straight Pipe Aluminized Cat-to-Axle X-Pipe Kit (11-14 GT)

Item 53804
AmericanMuscle no longer carries the Straight Pipe Aluminized Cat-to-Axle X-Pipe Kit (11-14 GT). Please check out 2015-2022 Mustang Mid-Pipes Exhaust for an updated selection.
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    Video Review & Installation

    Hey, guys. Today we're gonna be taking a look at and installing the Heartthrob Straight Pipe Cat-to-Axle X-Pipe Kit for 2011 to 2014 GT Mustangs. This kit gives you a 3-inch aluminized X-pipe to straight pipe over axle pipes. And on a scale of one to five, I'm gonna call this one a solid two. It's definitely louder than just an X-pipe alone upgrade because you are gonna be eliminating those resonators and the over axle pipes that you have. And do keep in mind that the sound that this produces will change and it will get louder depending on your axle-back setup. So, a lot of people upgrade their mid-pipe and their axle-back separately and that's gonna leave them with stock over axle pipes that have resonators in them. This kit gives you a way to upgrade your over axle pipes to straight pipes without having to purchase an entire cat-back. It cost about $380 and the install, I'll call it a two out of three wrenches on the difficulty meter just because it is a little bit difficult to get all these pieces on the car lined up perfectly. For this install, we used a 15-millimeter socket, a 13-millimeter socket, a 3/8 drive impact gun, and you guys might want a mallet just in case. All right, guys. So, to remove your factory H-pipe, what you're gonna need is a 13-millimeter for the two front bolts here and then you'll need a 15-millimeter for the clamps holding the back of the H-pipe. So, we're gonna go ahead, loosen these bolts here. All right. Now, all the clamps are loose and the H-pipe is ready to come out. So, we're gonna go ahead and wiggle it out of place. All right, guys. Now, we move towards the back of the car. We're gonna unbolt the over axle pipes so we can slide those out next. These also are loosened with a 13-millimeter. All right, guys. As you can see, the second this over axle pipe gets loose, it will fall down. So, just make sure you have a hand on it so it doesn't fall and hit the floor. All right, guys. So, here we have the Heartthrob system lying next to our stock setup here. First things first, you will be reusing the stock cats with the Heartthrob setup so that's always a plus. Saves a little bit of money and you don't have to worry about catalytic converters. Next thing is you are gonna be upgrading to an X-pipe, so your stock system has an H-pipe. The X-pipe is known to have more volume so it's gonna be louder and it gives you a little bit of raspy note. The H-pipe gives a deeper tone with less volume. Next thing is you are upgrading to a 3-inch system here, so this entire system is 3-inches. It's made from the aluminized tubing. It does have a coating on it. If you look at your over axle pipes next, the next thing you'll see is that these don't have any resonators in that these don't have any resonators in them. Your stock over axle pipes do have resonators and that's why they call this a straight pipe because you don't have any resonators here. So, not only are you getting more volume from switching over to an X-pipe, but you're also getting more volume from not having any resonators in your over axle pipe. And even those this is a 3-inch system, it will bolt up to your factory axle-back. So, you can run the factory axle-back with this or an aftermarket axle-back. That brings up a good point. If you guys aren't ready to purchase a full cat-back, this is always a really good option because you do get those upgraded over axle pipes that don't the resonators in them. A lot of times people just want a little upgrade in sound so they just swap out their mid-pipe. It doesn't really change the sound that much because you do have resonators in the over axle pipe. So, if you're looking for more of a sound change than just a mid-pipe would give you, then you wanna check out something like this. This is also a viable option if you aren't ready to purchase a full cat-back. So, the only way that you get upgraded over axle pipes like this is if you purchase a full cat-back or purchase over axle pipes separately. This is gonna give you a mid-pipe with upgraded over axle pipes. With all that being said, we're gonna go ahead and get this installed in the car. All right. So, before we get anything on the car, we're actually going to piece together our over axle pipes. You gonna wanna make sure you grab a clamp and we're gonna be just putting our tailpieces on that connect to the muffler onto our over axle pipes here. I'm just gonna slide this in here. I'm not gonna tighten any clamps at all actually until the very last step just because there are a lot of pieces here and you're gonna wanna make sure it all lines up perfectly. So, I'm literally just gonna have this tight enough so it holds the pipe in place.I'm actually gonna have to loosen this clamp a little bit. All right. So, we can still rotate the pipe if we need to. We're gonna go ahead and do the same thing on the other side. Now we'll do the same thing up here at the X-pipe. So, we have two 3-inch clamps here. We'll slide a 3-inch clamp over the X-pipe, grab our connecting pipe. Once again, I am gonna leave everything loose here. I will tighten it down enough just so that the pipes stay together, but I'm gonna leave it loose overall so I can adjust things. So, I'm actually gonna work backwards here when I go to put this on the car. I'm gonna start with the over axle pipes first. I'll make the connection to the stock axle-back and then I'll move forward and go from there. I do have two pole jacks under here with me, so I'm gonna snake the over axle pipe up and into place, make the connection at the axle-back, and then use my pole jack to hold the over axle pipe up and into place. All right, guys. So, at this point, I have the over axle pipe in place. You can see I have my pole jack here holding everything up and straight. I'm gonna just try to get it as straight as I can right now right off the bat. I am gonna tighten this clamp right here where I'm connecting at the axle-back just because I have a really good connection right here. I'm gonna leave my other clamp loose right now though. All right. So, now, we're gonna get the driver side over axle pipe in place. We're gonna do the exact same thing that we did on the other side. All right. So, once again, we are going to tighten this clamp right here at the axle-back. Next, we have to get our mid-pipe assembly in place. So, what I'm gonna do first is I'm gonna take the last four clamps that we have and just slide them over to the pipes before I try to get the mid-pipe in place. All right. So, now we are going to get our mid-pipe in place. So, first, I'm gonna slide into my over axle pipes and then, I'll try to make the connection at the cats. All right, guys. So, at this point, this is where all of your adjustment comes into play. You guys can see I'm a little bit off here. I have everything slid into place, but it all needs to sort of go backwards at this point. So, this is why we left all of the clamps loose so now, we can adjust so we can make all of our connections. All right. So, now, we have everything lined up and in place, we just have to go through and tighten our clamps. And I will say, guys, getting this lined up and perfectly straight is gonna be the hardest part of the install. You could spend a good amount of time doing this. And the way that I did it working from the back to the front is just one way to do it. You guys can do it the opposite way. You can work from the front, go to the back. You can leave your axle-back up. You can drop your axle-back. It's all whatever is gonna work for you. So, you may try it one way, it may not work. Just know that getting these pipes together will be the hardest part of the install, getting it straight, all lined up, and fitting perfectly will take some time. So now we're gonna go ahead. We're gonna tighten our clamps up here and then we're gonna go through the whole system and tighten everything down. All right, guys. That's gonna wrap up this review and install. Keep in mind that you can always check this out more online right here at

    Product Information

    Features, Description, Q&A, Specs & Installation


    • Improves Exhaust Flow for More Power
    • Race Car Growl
    • Aluminized Steel Construction
    • Clamp-On Design
    • Reuses Stock Catalytic Converters
    • Uses O.E. or Aftermarket Axle-Back
    • Fits 2011-2014 GT Mustangs


    Better Flow, More Power. Ford actually did a decent job on the Mustangs catalytic converters, but the stock H-Pipe is pretty restrictive. That's where the Heartthrob Straight Pipe Cat-to-Axle X-Pipe Kit comes into play. Featuring a X crossover and 3" free-flowing mandrel-bent piping, this Heartthrob Mid Pipe will dramatically improve exhaust flow for more power and sound that you can feel.

    Race Car Growl. This free flowing Heartthrob Cat-to-Axle X-Pipe Kit for the 2011-2013+ GT Mustang's not only increases power, but it also adds a loud raspy, race car growl to the sound of your exhaust with its modern "X" crossover pipe design.

    Reuses Stock Cats. The installation of the Heartthrob Exhaust cat to axle system requires removing the stock exhaust piping from the catalytic converters back to the axle-back, and reuses the factory catalytic converters saving you money. Clamps and instructions are provided.

    Versatile Design. The unique design of the Heartthrob Cat-to-Axle exhaust kit allows you to install the axle-back of your choice. You can keep the stock mufflers for a mild sound or go with a set of muffler deletes for a wild sound. The choice is up to you.

    Durable Construction. Heartthrob uses free-flowing 3" diameter CNC mandrel bent aluminized tubing with a merged X crossover and high flow straight pipe design to improve exhaust flow to provide a significant increase in power and sound.

    Application. This Heartthrob Straight Pipe X-Pipe Kit is designed to fit the 2011-2014 GT Mustangs with either the stock exhaust manifolds or aftermarket shorty style headers installed.

    CA Residents: WARNING: Cancer and Reproductive Harm -

    Installation & What's in the Box

    Installation Info

    What's in the Box

    • (1) X-pipe
    • (2) Down Pipes
    • (2) Over axle pipes
    • (2) short pipes
    • (10) Clamps

    Tech Specs

    Mid Pipe Specifications
    Style Mid Pipe: "X" Type Headers Required: Shorty or Stock Manifolds
    Piping Material: Aluminized Steel Piping Size: 3"
    Catalytic Converter: Reuses stock Catalytic Converters Fitment: 2011-2014 GT Mustangs

    Questions & Answers

    10 More Questions

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