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Stainless Works Performance Catted Downpipe (15-20 EcoBoost)

Item 387449
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    Features, Video & Details

    • Stainless Works Catted Performance Down Pipe
    • Increases Rear Wheel Horsepower and Torque
    • High Flow Catalytic Converter
    • 304 Stainless Steel Construction
    • Free Flowing 3" Diameter Mandrel-Bent Tubing (Steps Down to 2.25")
    • More Aggressive Sound Compared to Stock
    • Designed and Manufactured in the USA
    • Is NOT CARB Certified
    • Fits 2015-2020 EcoBoost Mustangs w/ 2.25" Cat-Back Exhaust

    Review & Installation Video

    Review & Install Video

    Hey, guys. Stephanie with here with a Stainless Works Performance Downpipe that's available for all 2015 and up Ecoboost Mustangs. The Stainless Works Downpipe is going to be for the Ecoboost owners who are looking to upgrade that restrictive factory downpipe, but still keep a factory or factory like Catback setup. The factory setup around the turbo is pretty constricting so opening up some of that airflow from the turbo can provide some pretty handy performance improvements. Basically when it comes to the turbo, if you're looking for performance, you're pretty much gonna want airflow as unrestricted as possible so the turbo can spool quickly. And the faster the turbo can spool, the more gains you'll see. So like I hinted at earlier this downpipe comes either catted or non-catted and we have the catted version here today.Looking at it closer, the first thing is this is a full three inches all the way down to the step-down right here. The step-down is gonna reduce three inch down to a two and a quarter inch which leaves the option of keeping a stock Catback or running an aftermarket two and a quarter inch one, and that's one of the nice things about this downpipe. You can pick up the downpipe for some performance gains without having to purchase a complete new Catback while you're at it unless you want to that is. And Stainless Works also has a full three inch option out there too if you want to go with a Stainless Works Catback. The three inch portion up here is larger than the factory downpipe, which is where the less restriction comes from. And if you pick up the uncatted version, that's gonna be even less restrictive.But even the catted version does have a high flow cat which is more free flowing than the factory cats are. This is also fully made with 304 stainless steel, which is nice for those Mustangs that see all different types of road conditions, and the pipe is manual bent as well, just to help with smoother air flow. When using the off-road version, you will definitely need a tune since you're deleting the cat. And if you're going with a catted version, you can run it without a tune, but keep in mind that you'll see the full power potential behind upgrading a downpipe when you're running these with a tune regardless of whether or not it's catted.So even though the main idea behind an aftermarket downpipe is to help give the turbo unhindered airflow, swapping out your factory downpipe is also going to give you more sound too, especially if you're running the uncatted version. This downpipe is right in the middle of the road when it comes to price if we compare it to the other options that are out there right now. It costs between $450 and $550 depending on if you go with the off-road or the catted version with the off-road version being less expensive. When it comes to the install, luckily, this isn't a bad one. You're probably looking at a few hours to get everything done, and I'm going to call this a one out of three wrenches on the scale. This is obviously going to be easier to do on a lift but, of course, you can get the job done on jack and stands if you don't have access to one. You won't need anything out of the ordinary, just a few sockets, wrenches, and a short extension. You're gonna be removing the front and rear O2s for the install, but I'd just make sure to unclip those before you remove or reinstall them so you aren't twisting the wires. And of course, don't forget to grab the factory downpipe gasket before installing the new downpipe since sometimes a gasket can stick to the turbo. The only other thing I'd say here is to align the new downpipe up first before tightening everything down, but that's about it. Only a few bolts and not a whole lot of time for the install.So wrapping things up here this is a three inch downpipe that steps down to work with a two and a quarter inch Catback. It comes either catted or non-catted depending on what you're looking for. And not only is this gonna increase performance, but it's also going to open up some sound on the Ecoboost as well. You can check this out more online for yourself and see what you think. I'm Stephanie, and for all things Mustang, keep it right here at

    More Horsepower And Torque. Add even more horsepower and torque to the rear wheels of your turbocharged EcoBoost Mustang by installing a Stainless Works 3" Performance Catted Down Pipe. A Stainless Works Catted Down Pipe features a high flow race catalytic converter to increase the overall performance of your S550 Mustang.

    More Aggressive Sound. Stainless Works Performance Down Pipe not only helps increase power and performance, but it also adds a much more aggressive exhaust note to your S550 EcoBoost Mustang, when compared to the stock down pipe.

    Stainless Steel Construction. Manufactured in the USA from 3" diameter T304 stainless steel tubing for strength and superior corrosion resistance, this Stainless Works Catted Down Pipe is mandrel bent for superior airflow - so there are no kinks to rob you of power.

    Recommended Upgrade. To realize the full power potential that this Down Pipe has to offer, AmericanMuscle recommends a Bama custom tune with a Mustang Handheld Tuner to reprogram the vehicles computer (ECU) for proper operation.

    Application. This Stainless Works 3" to 2.25" Performance Catted Down Pipe is specifically designed to fit the 2015-2020 EcoBoost Mustang with the stock exhaust or a 2.25" catback system installed.

    Fitment: 2015 2016 2017 2018 2019 2020 Details


    CA Residents: WARNING: Cancer and Reproductive Harm -

    What's in the Box
    • (1) Off-Road Down Pipe
    Installation Info
    Tech Specs
    Down Pipe Specifications
    Piping Material:Stainless SteelPiping Size:3" (steps down to 2.25")
    Catalytic Converter:"Yes"Type Cat-Back Required:Stock or 2.25" aftermarket 
    -Fitment:2015-2017 EcoBoost
    Will it fit my Mustang?

      Customer Photos

        Questions & Answers (6)

        5 Top Rated Questions

        I already have a 93 octane tune in my mustang would I have to retune it when I get this put onn

        Will this work with the Flowmaster cat-back exhaust?

        • So long as the Flowmaster cat-back system is 2.25", yes, it will fit.

        Helpful (0)

        Will this fit with the scavenger outlaw y-pipe?

        • Yes, as this steps down to the 2.25" piping it will work with the Scavenger Series Y pipe.

        Helpful (0)

        Is the Stainless Works Performance Downpipe- Catted street legal? also with the step down from 3in to 2.25 will the t304 steel of the down pipe be compatible with my Borla ATAK T304 steel cat back?

        • The Stainless Works Performance Downpipe - Catted uses a high flow catalytic converter in order to improve performance, so it would not be as efficient as the factory catalytic converter at reducing emissions. The Stainless Works Performance Downpipe - Catted will be compatible with all 2.25" catback systems, although keep in mind that occasionally mixing exhaust manufacturers may result in the necessity for some slight modification which can be easily done by an exhaust shop for proper fitment.

        Helpful (0)

        I'm planing on getting the "MAGNAFLOW COMPETITION CATBACK EXHAUST (15-16 ECOBOOST)" will this catted downpipe fit? so I can get the exhaust and this downpipe installed at the same time. Thank you

        • Yes, I got the same one.

        Helpful (0)
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        1 More Question
        Will this fit my borla atak cat back exhaust on my 2015 ecoboost? 1 answer

          Customer Reviews (2) Write a Review

          Overall Rating 4

          out of 5 stars

          Installation Time:Full Day

          • Loudness / Volume 3.5 3.5
          • Exhaust Note 4.5 4.5
          • Fit & Finish 4 4
          • Bang For Your Buck 4.5 4.5

          • 4/5

            Installation Time: Shop Install

            April 02, 2019

            It works, once you get it on.

            So, I bought this to install before i got my pony on a tune to save a little money. Reviews looked good and it was a single piece, which is what i was looking for. I knew i didn't want a two piece pipe. Got this and took it to a lift to install myself. Worst part about having to get this part on was definitely taking the stock piece off. Bolts were torqued far too much and took 2.5 hours just to get everything off. When putting this part on, everything looked good, until you get to the exhaust. Connecting piece was about .5 inches too big, and even with the clap they give, there is no way it was staying on. This error might have been my fault, since no one else seemed to have this issue. If i was sent the wrong piece, it was still able to be salvaged, so i didn't care too much. The life i took it to was in a military base, and time wouldn't allow me to go back for another few weeks, so instead i just bit the bullet and took it to a shop. Since i already had a pipe, the install was about $125 after tax and was completed within the day. Shops will differ, and while i would have loved to install myself, it at least was not a complete bust. As for the actual performance and sound, it is amazing. Getting the pipe on might have been annoying, but this was well worth it. I'm not a huge fan of a car being loud all the time, more of a quiet until you want to make noise person. This makes the car louder, no doubt about that. Sound is a low rumble, still louder, but definitely not deafening. Performance wise, this is a heavy hitter. Obviously this won't change anything like top speed with a governor, or anything else, but it does help the acceleration. Any pull so far has seen drastic improvements. I've tried pulls at a standstill, 30, 60, and 90 mph. All had improvements. When it was first installed there was a slight smell from the cat being broken in, but was completely gone within the first two days. Overall, I think this is a great buy, and should be easily able to be installed on any ecoboost.


            Year: 2017 Submodel: EcoBoost

            Helpful (0)

          • 4/5

            Installation Time: Less than 1 Hour

            December 21, 2015


            It was very easy to install. Added a little aggressive sound and a slight back fire. Makes my car get up and go a lot faster. I'm very happy with my purchases.


            Year: 2015 california

            Helpful (15)

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