The factory exhaust manifolds on your S550 Mustang GT are a known restriction. Speed Engineering's 1-7/8" longtube headers replace them with a free-flowing, direct-fit stainless system that unlocks real horsepower, improves throttle response, and gives your Coyote the exhaust note it deserves. Paired with a 3" off-road X-pipe that connects directly to the existing axle-back location, this is a complete bolt-on system — everything you need is in the box.
Dyno proven to gain over 25 rear-wheel horsepower. Built from 304 natural stainless steel with mandrel-bent primary tubes, CNC-machined port-matched flanges, and full TIG-welded construction.
Kit Includes:
- 1 Pair of 1-7/8" Stainless Longtube Headers
- 1 Three-inch Off-Road X-Pipe / Connection Pipe
- 2 MLS Exhaust Gaskets
- 2 O₂ Sensor Extension Harnesses
Optional: Zinc Coated Header Bolts (M10x1.5) can be added at the time of purchase.
Features:
- 1-7/8" Port-Matched Primary Tubes — Full-diameter flow from cylinder head to collector for maximum exhaust scavenging
- 3" Collector with Collector Merge Spikes — Optimized merge geometry for strong low-to-mid RPM torque
- Mandrel Bent Tubing — Consistent tube diameter through every bend; no crimping, no restriction
- CNC Machined Port-Matched Flanges — Precision fit at the head and collector for a leak-free seal
- 304 Natural Stainless Steel Construction — Corrosion resistant, heat tolerant, and built to last
- Longtube Header Design — Maximum scavenging efficiency vs. shorty or mid-length headers
- Dyno Proven — 25+ RWHP gain on 5.0L Coyote applications
- V8 Only — Compatible with 5.0L Coyote engines only
Important Installation Notes:
- O₂ sensor extension harnesses are required and included — upstream O₂ bungs will be located further back with longtube headers
- Rear downstream O₂ sensors will no longer be used — a check engine light for catalyst efficiency will appear and must be disabled via PCM tuning
- Header bolt thread pitch varies by Coyote generation — verify before installation:
- Early Gen 1 (2011) and some Gen 3 (2018+): M10x1.25
- Late Gen 1 (2011) and Gen 2 (2015–2017): M10x1.5
Vehicle Applications:
Ford Mustang GT — 5.0L Coyote (RWD)
- 2015 Ford Mustang GT (RWD) — 5.0L Coyote
- 2016 Ford Mustang GT (RWD) — 5.0L Coyote
- 2017 Ford Mustang GT (RWD) — 5.0L Coyote
- 2018 Ford Mustang GT (RWD) — 5.0L Coyote
- 2019 Ford Mustang GT (RWD) — 5.0L Coyote
- 2020 Ford Mustang GT (RWD) — 5.0L Coyote
- 2021 Ford Mustang GT (RWD) — 5.0L Coyote
- 2022 Ford Mustang GT (RWD) — 5.0L Coyote
- 2023 Ford Mustang GT (RWD) — 5.0L Coyote
FAQ
What is included in this kit?
The kit includes a pair of 1-7/8" stainless longtube headers, a 3" off-road X-pipe, two MLS exhaust gaskets, and two O₂ sensor extension harnesses. Zinc coated header bolts (M10x1.5) are available as an optional add-on at the time of purchase.
Will I get a check engine light after installing these headers?
Yes. The rear downstream O₂ sensors are no longer used with this system, which will trigger a catalyst efficiency code. This must be resolved through PCM tuning — it cannot be cleared by simply resetting the ECU.
Do I need O₂ sensor extensions?
Yes, and they are included in the kit. The upstream O₂ sensor bungs are positioned further back with longtube headers, so extensions are required for proper sensor placement.
How much horsepower do these headers add to a 5.0L Coyote Mustang?
Speed Engineering's 1-7/8" longtube headers are dyno proven to add over 25 rear-wheel horsepower on 5.0L Coyote applications compared to stock exhaust manifolds.
What header bolt size do I need for my Mustang GT?
It depends on your Coyote generation. Early Gen 1 (2011) and some Gen 3 (2018+) engines use M10x1.25 bolts. Late Gen 1 (2011) and Gen 2 (2015–2017) engines use M10x1.5 bolts. Verify your thread pitch before installation.
Will these headers work with my existing axle-back exhaust?
Yes. The 3" X-pipe included in the kit connects directly to the factory axle-back location, making this a bolt-on system compatible with most aftermarket and stock axle-back setups.
Are these headers street legal?
No. These are race-only headers intended for closed-course competition use only. Installation on a street-driven vehicle may violate the Clean Air Act (42 U.S.C. 7522(a)(3)).
⚠️ Race Use Only: This product is manufactured and sold for installation on vehicles used solely for competition. Once installed, the vehicle may not be used, registered, or licensed for use on a public road or highway. Installation on a street-driven vehicle may violate the Clean Air Act 203(a)(3), 42 U.S.C. 7522(a)(3).
