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Kooks Long Tube GREEN Catted Headers (15-17 GT)

AmericanMuscle no longer carries the Kooks Long Tube GREEN Catted Headers (15-17 GT). Please check out 2015-2019 Mustang Long Tube Headers for an updated selection.
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Features, Video & Details

  • Increases Rear Wheel Horsepower and Torque
  • Long Tube Header Design
  • Catted Connection Pipes Included
  • High Flow GreenCat Catalytic Converters
  • Free Flowing Mandrel-Bent Tubing
  • 304 Stainless Steel Construction
  • 3" Collectors w/ Scavenging Spikes
  • Choice of 1-3/4" or 1-7/8" Primary Tubes
  • Made with Pride in the USA
  • Fits Left Hand Drive Models Only
  • Fits 2015-2017 GT Mustangs

Review & Installation Video

Review & Install Video

Hey guys, Stephanie from, here with a review of these Kooks Long Tube Headers with Kooks Green Catted connection pipes, available for 2015 and up S550 GT Mustangs. In this video, we're going to be looking at a few different things in regards to these headers. We're going talk about the materials and construction of the headers themselves, and the install too. We'll talk more about this later, but I can tell you right now that long tube headers make for a difficult install, so I'm gonna call this one a three-out-of-three-wrenches in the difficulty meter. The Kooks long tube headers with the GREEN catted connection pipes are gonna be a good option for someone looking for a natural finish long tube, that's not only going to maintain the use of cats but that also offers a high-flow cat that's designed to meet the EPA emissions requirements. Long tube headers are going to offer both performance and sound gains, but the end result of your headers will depend on the rest of your setup. The runners on these particular headers are one-and-three-fourths-inch, which is slightly different than the one-and-seven-eighth-inch offering that Kooks offers with these same connection pipes. Traditionally you see forced induction cars running the larger runners, and NA cars running the one-and-three-quarter-inch runner, but I wouldn't really say that that's a hard and fast rule, especially with the new coyote motors. So you don't have to have a blower to run a one-and-seven-eighths-inch diameter runner, you just need to keep in mind your current mods and the goals you have for your car when you're looking around for long tubes, as well as what going with this size runner, will do to your power band with the mods that you have. If you have some bolts on and you're still NA, you might see a hit on your low-end torque, but once you spin the coyote motor up, this diameter's gonna help keep these things moving, and that's where you're gonna see top end gains. Getting into the specifics here, these are 304 stainless steel headers that have a natural or raw finish, which is gonna be different than a chrome or a ceramic coated header. It obviously doesn't have the polished appearance that a chrome header would have. And while these don't have the ceramic coating either, they are made from that 304 stainless steel tubing, so you won't have to worry about corrosion. Not to mention, you get to see the beautiful welds since these have that raw finish, and this is mandrel bent tubing which is gonna help with smoother air delivery. The primary tubes then merge down to three-inch collectors with the scavenger spike. Kooks always uses scavenging spikes just to make sure that the headers will flow perfectly. And then Kooks uses a ball and socket design here for a tight and leak-free fit, then you have your connection pipes here. Like I said earlier, they are three-inch and they are catted, and these aren't your normal high-flow race cats, though. These are GREEN cats or cats that Kooks has developed that are high performance, but still meet the stringent EPA emissions standard. These cats are gonna work well on both force induction and on NA cars, and they do have a high rate of eliminating the emission related check engine light issues. So the connection pipes start at three-inch, but you can see that they do step down right here. They're gonna step down to two-and-a-half-inches so you can run an aftermarket two-and-a-half-inch cat back or mid-pipe. And if you didn't know already, when you change your header setup to a long tube setup, you also need to change your mid-pipe to a shorty mid-pipe in order to work with the long tubes. So just keep the two-and-a-half-inch requirement in your mind when you pick up your cat back or your mid-pipe. If we move on to price, as we all pretty much know, or you know if you've been shopping for long tubes, that they're pretty much gonna be a solid investment. They're pricey and they're difficult to install. The option from Kooks, since they are a higher quality item that's more at the top of the food chain, are going to be on the more expensive side. The one-and-three-fourths option that we have here are gonna be slightly less expensive than the larger diameter primary option, which isn't unusual. You do tend to see the larger runner costing more than the smaller ones, but not usually by very much at all. You'll be spending a touch over $2200 for a set of these, but do keep in mind that you still need a shorty mid-pipe in order to install these, so you can figure on purchasing that as well. And that's why I called long tube headers an investment earlier, but you do have to keep in mind all the benefits and power that you'll be getting from this set-up. And to put things in perspective, it's not just Kooks that's gonna be expensive. You're gonna be looking at headers costing over a grand anyways. As for the install on this one, long tubes are always gonna be a difficult install. I don't say this often, but if you don't have a helping hand, and you don't have much experience, it might be better just to take the car to a shop for the install. If you do tackle this yourself, it's gonna be a full three-out-of-three-wrenches on the scale and a day in the garage. Especially considering you'll be installing either a mid-pipe or a cat back with these headers. You can do it on a jack and stands but a lift will make it easier for sure. You're gonna need your toolbox for this one, with an assortment of different sockets, wrenches, and extensions. You're looking at things like disconnecting the steering shaft, dropping the starter, and removing a motor mount. A lot of this install obviously requires working in some pretty tight areas, so while everything is straight forward, getting access and maneuverability in these areas is actually tricky which is why you need to pull a motor mount on one side, so you can raise the motor slightly with a jack to give you a little bit more room. Having a helping hand, in this case, is really gonna benefit you. But a day of wrestling and some pretty pennies spent on these mods is totally worth it in my opinion. So, wrapping things up with the Kooks long tube headers, these are 304 stainless steel headers with high-flow GREEN cats. There are one-and-three-fourths-inch runners and three-inch collectors that run down to three-inch connecting pipes that then step down to two-and-a-half-inches. This lets you keep your stock catback or pair this system with an aftermarket catback. As usual, you can check them out more online for yourself right here at

Improves Horsepower and Torque. As if your Coyote Powered GT doesn't have enough tire shredding power already, you can now add even more by installing a set of Kooks Long Tube Headers that include GreenCat Catted Connection Pipes. Kooks engineered their free flowing Headers with a 3" collector and EPA friendly GreenCat catalytic converters to significantly improve the exhaust flow of your V8 Mustang, when compared to the restrictive factory manifolds. These Long Tube Headers are ideal for those Mustang owners who really want to uncork all the power and torque hiding inside their Mustang's 5.0-liter Coyote engine.

Green Catalytic Converters. GreenCats are Kooks ultra high performance green catalytic converters. Kooks specifically designed these Catalytic Converters to meet stringent EPA Federal Emissions Standards. Able to handle exhaust temperatures of up to 1500F, these GreenCats work exceptionally well on both force inducted and naturally aspirated Mustangs. GreenCats have a 90% success rate of eliminating emission related "Check Engine Light" issues.

Choice of 1-3/4" or 1-7/8" Primaries. Kooks offers their GreenCat Catted Long Tube Headers in a choice of two sizes. Kooks Headers are available with either 1-3/4" or 1-7/8" primary tubes. 1-3/4" primary tubes are recommended for naturally aspirated applications. Where 1-7/8" primary tubes are recommended for force inducted and heavily worked engines. The choice is yours - Please select from the options listed above.

Quality Construction. Kooks proudly manufactures their Exhaust Systems right here in the USA. These Kooks Long Tube Headers are constructed from free flowing CNC mandrel-bent 304 stainless steel for optimal exhaust flow. The primary tubes merge into a 3" collector that features a scavenger spike to increase power and performance. These headers feature a ball and socket design for a tight leak-free fit. Green Catted connection pipes are included.

Calibration Required. Installation of these Kooks Long Tube Headers will require the use of a Handheld Tuner to reprogram the vehicles computer (ECU) for operation. By reprogramming your Mustangs ECU you will be able to realize the full power potential that these Long Tube Headers have to offer.

Application. These Kooks Long Tube Headers with GreenCat Catted Connection Pipes are specifically designed to fit the 2015 to 2017 GT Mustangs equipped with the DOHC Coyote 5.0L V8 engine. These Headers are intended to be installed with the factory or an aftermarket 2.5" exhaust system.

Technical Note. This product is not legal for use in California or any other state adopting California emission standards. Not legal for use on pollution controlled motor vehicles; intended for off road use only. These Headers are intended for left hand drive applications only.

Fitment: 2015 2016 2017 Details

CA Residents: Warning: California's Proposition 65

What's in the Box
  • (2) Long Tube Headers
  • (1) Catted Connection Pipe Assembly
  • (2) Gaskets
  • (2) Clamps
  • (16) Small Bolts
  • (8) Flat Washers
  • (4) Long Bolts
  • (4) Nuts
  • (1) O2 Connector
Installation Info
Tech Specs
Header Specifications
Header Type: Long Tube Type Mid Pipe Required: Stock Factory
Material: 304 Stainless Steel Finish: Natural
Catalytic Converter: "Yes" - For off-road use only Fitment: 2015-2017 GT Mustangs
Will it fit my Mustang?

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Customer Photos

Questions & Answers (4)

4 Top Rated Questions

Are they compatible with 2018 GT

  • Unfortunately, these Kooks Long Tube GREEN Catted Headers are specifically designed for 15-17 GT Mustangs and will not fit a 2018 GT.

Helpful (0)

Can I pair this green cat headers with borlas 3inch cat back?if not what would I need to do so

  • In order to pair these headers with a 3 inch tubed cat-back you would need to use the Flowmaster Venturi Reducer Cone, which I will link below. The other option would be to purchase either the headers with the 3 inch mid-pipe connection or the cat-back with 2.5 inch tubing. Flowmaster Venturi Cone:

Helpful (0)

Will these be compatible with corsa extreme catback

  • The Kooks long tube green catted headers will bolt up to the Corsa extreme catback system.

Helpful (0)

Is there any sort of adapter that can be purchased for this to work with a 3 in. exhaust system?

  • These Headers are intended to be installed with the factory or an aftermarket 2.5" exhaust system.

Helpful (0)
Post Your Question

Customer Reviews (2) Write a Review

Overall Rating 5

out of 5 stars

Installation Time:Weekend

  • Loudness / Volume 5 5
  • Exhaust Note 5 5
  • Fit & Finish 5 5
  • Bang For Your Buck 5 5

  • 5/5

    Installation Time: Weekend

    May 20, 2017

    It's all sound and performace

    I did on floor you don't have to remove Sterling shaft Please please do not used any stud please use bolts only and take you times Top three on drive side remove air intake you will see a Please take you time Used jack and ramps


    Year: 2016 Submodel: Other

    Helpful (4)

  • 5/5

    August 17, 2016

    Worth it

    I bought these because my locality has bi-annual emissions testing and a CEL or failed readiness check will fail. The headers are beautifully welded and crafted. The included hardware is above anything else I've seen on other makes of headers. The installation is fairly involved and took me most of the day. There were zero installation issues and everything bolted right up--including to my Magnaflow cat-back. Be sure and use the locking tabs for the Stage 8 hardware. Sound? Loud! It's made the car loud enough that I'm debating on a quieter cat-back to lessen the noise. It's not bad noise, I'm just old and my car is a daily. Your exhaust sound will deepen a little and develop a rasp at higher RPMs. On the performance side, the car definitely opened up and I'm pleased. I do not have a tune. A few weeks in and no CEL (knock on wood). I'm hoping it stays that way. It's fixable, but I'm of an age I don't feel like gaming the system anymore. I highly recommend doing some searching for the best price.


    Year: 2015 Submodel: GT

    Helpful (11)

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