Free Shipping On Orders Over $75. Details

Talk to a Mustang Enthusiast
M-F 8:30A-11P, Sat-Sun 8:30A-9P
$5,000 Up for Grabs! Enter to Win >

Kooks 1-5/8 in. Long Tube Headers w/ Off-Road X-Pipe (05-10 GT w/ Manual Transmission)

Item 65501
AmericanMuscle no longer carries the Kooks 1-5/8 in. Long Tube Headers w/ Off-Road X-Pipe (05-10 GT w/ Manual Transmission). Please check out 2015-2021 Mustang Headers for an updated selection.
Call a Mustang Enthusiast at 1-877-887-1105
M-F 8:30A-11P, Sat-Sun 8:30A-9P

    Video Review & Installation

    The Kooks Long Tube Headers and Off-Road X-Pipe would be a great choice for those manual 2005 to 2010 GT owners who are looking for a little bit more power and a lot more sound when using a premium product. Now the Kooks will deliver top-notch 304-grade stainless steel throughout and a killer build quality for the $1200 to $1300 price point.Install, on the other hand, will get a full-pull three outta three wrenches on the difficulty meter and at least a full day or two to get everything knocked out.So in my humble opinion, Kooks is one of the top header options for Mustang owners out there, as their fitment, the build, and also the quality, are all completely top notch. And the same can be said about the long tube headers we have here for the 3-valve, in addition to the off-road or catless midpipe. But because this is going to be more of a general overview here, we're not gonna have any chassis dyno numbers for you guys. Sorry about that. But with that being said, it's not uncommon for the manual 3-valve cars to pick up anywhere between 10 to 20-wheel horsepower with a quality tune which, by the way, is highly recommended when going with an off-road x-pipe like this.Now ultimately your final power numbers will vary due to a number of factors, including different modifications and, of course, that tune, but a decent bump should be expected.Now one thing I can absolutely guarantee, on the other hand, is the massive increase in sound and volume when switching to a long tube header and off-road x-pipe combination like this. On top of melting eardrums for miles around, it's also gonna produce a little bit more rasp when compared to a catted setup per se, in addition to a set of factory or even shorty manifolds.One thing to point out here with the Kooks long tubes is that they do feature the 1 5/8-inch primary or runner size, which is a very popular size for the 3-valve cars, no doubt, but it's also the smallest primary in the category. Your other options will be a 1 3/4-inch header, a 1 7/8-inch option, and finally a massive 2-inch option from LTH.But let's talk a little bit more about the construction. And again, guys, in my opinion, the Kooks stuff is going to be one of your nicer options that you'll encounter in the category from a build standpoint. This does include, of course, that 304-grade stainless I briefly mentioned earlier, mandrel-bent primaries...all one piece, by the way, I really like that. Beautiful welds, including here at the 3/8-inch laser-cut flange. And those welds inside the flange have all been smoothed out, which is great because you don't wanna create a more turbulent exhaust flow. You wanna keep that velocity up and keep flow moving throughout the header. And they've also incorporated their merge spike technology to help increase that overall. You're also looking at 2 1/2-inch mandrel-bent tubing here, guys, and a 304-grade stainless for the off-road or catless midpipe which, by the way, is designed to work with that factory cat-back or maybe an aftermarket cat-back that does utilize that factory-style connection.Now, I do wanna point out this is an off-road version, again, and that just simply means that there won't be any cats included with this system. And therefore, it is designed more for "off-road" use only.Now if you love everything about the Kook stuff here but wanted to grab something that will be maybe a little bit more inspection-friendly, Kooks does offer a catted version that can also be found here on the site for a few bucks more.Now as far as your installation is concerned, well, just know that it will involve a decent amount of time and effort. So again, call this one a full three outta three wrenches on the difficulty meter along with at least a full day in the shop or garage, probably two, to remove those factory manifolds and get the new Kook system in place.So wrapping things up here, guys, if you're looking for a quality 1 5/8-inch setup and midpipe combo for your manual 3-valve Mustang, then be sure to check out the Kooks Long Tube Header options right here at

    Product Information

    Features, Description, Q&A, Specs & Installation


    • Increase Rear Wheel Horsepower and Torque
    • Includes Headers w/ Matching Off-Road X-Pipe
    • 304 Stainless Steel Construction
    • For Off-Road, Track Use
    • Free Flowing Mandrel-Bent Tubing
    • Fits 2005-2010 Manual GT Mustangs


    Improve Horsepower And Torque. The Kooks Long Tube Header and Off-road Shorty X-pipe combo kit for the manual 2005 to 2010 GT Mustangs will balance out the exhaust pressure to increase flow over the restrictive stock exhaust system resulting in more horsepower, torque, and better throttle response.

    Quality Construction. Manufactured from 1-5/8" mandrel bent 304 stainless steel tubing Kooks Long Tube Headers are TIG welded for strength, and feature a leak-free ball flange design to fit perfectly into the included 2.5" diameter 304 stainless steel Shorty X-pipe for excellent exhaust flow and performance.

    Recommended Upgrade. To realize the full power potential that this Header and X-pipe combo kit has to offer, AmericanMuscle recommends a custom tune with a Mustang Handheld Tuner to reprogram the vehicles computer (ECU) for proper operation.

    Application. This Kooks Header and matching Off-road X-pipe combo kit is designed specifically for the 2005 to 2010 4.6L GT and Bullitt Mustangs equipped with a manual transmission.

    Technical Note: This Kooks product is intended for off road use, and is not legal for use in emission restrictive states.

    CA Residents: WARNING: Cancer and Reproductive Harm -

    Installation & What's in the Box

    Installation Info

    What's in the Box

    Hardware included:
    • Kooks Long Tube Headers
    • Matching Kooks X-Pipe
    • Necessary Gaskets
    • O2 Extensions

    Tech Specs

    Header Specifications
    Header Type: Long Tube Finish : 304 Stainless steel
    Type Mid Pipe Required: Kooks Shorty X Fitment: 2005-2010 GT - Manual

    Mid Pipe Specifications
    Style Mid Pipe: Shorty "X" Type Headers Required: Kooks Long Tube
    Piping Material: 304 Stainless Steel Piping Size: 2.5"
    Catalytic Converter: "NO" - For off-road use only Fitment: 2005-2010 GT - Manual

    Questions & Answers

    10 More Questions

        Related Mustang Categories