Kooks Headers 15-26 Ford Mustang 5.0L OEM Resonator Delete H-Pipe Kit

Remove the Factory Resonator Box and Unlock a Deeper, Muscle Car Exhaust Note on Your 5.0L Coyote

The Kooks 11513500 OEM Resonator Delete H-Pipe replaces the heavy, restrictive factory resonator assembly on 2015 to 2026 Ford Mustang GT and related 5.0L 4V Coyote models with a mandrel-bent, 304 stainless steel H-pipe that connects directly to the OEM headers on the inlet side and the factory axle-back system on the outlet side. No cutting of the primary exhaust piping is required at the header collectors; this kit uses included adapters and clamps to bridge the OEM mid-pipe connection points, preserving the factory catalytic converters upstream while eliminating the resonator that deadens tone and adds weight. The result is a significantly deeper, more aggressive exhaust character at idle and part-throttle without the raspy drone or volume increase associated with muffler deletes, making the 11513500 one of the most effective single-component tone improvements available for the S550 and S650 Mustang GT platform.

Kooks built this kit from 3 inch 16-gauge 304 stainless steel mandrel-bent tubing with a 2.25 inch outlet connection that interfaces with the OEM axle-back exhaust using OEM-style band clamps. The H-crossover design balances exhaust pulses between the two cylinder banks, which is the primary reason an H-pipe produces that characteristic low-frequency muscle car sound versus the sharper, higher-frequency tone of an X-pipe. This H-pipe ships with the mid-pipe adapters and all clamps necessary for installation on a stock-equipped Mustang GT; no cutting, welding, or tuning is required. It fits the GT, GT Premium, Bullitt, Mach 1, and Dark Horse submodels across the 2015 to 2026 model range, covering both the S550 and S650 chassis generations of the 5.0L 4V Coyote-powered Mustang.

Key Features

• Direct OEM Resonator Replacement: The 11513500 bolts directly between the factory catalytic converters and the OEM axle-back exhaust with no cutting or welding required on the primary exhaust piping.
• 3 Inch 304 Stainless Steel Mandrel-Bent Tubing: 16-gauge construction maintains smooth interior surface curvature through every bend to minimize turbulence and maximize exhaust gas velocity.
• H-Pipe Crossover Design: Balances exhaust pulses between cylinder banks for a deeper, lower-frequency muscle car tone versus the sharper sound profile of an X-pipe configuration.
• Retains Factory Catalytic Converters: This kit connects downstream of the OEM cats, preserving emissions compliance on vehicles in 49-state-registered markets.
• Includes All Hardware for Installation: Ships with 2.25 inch to 3 inch mid-pipe adapters and all band clamps necessary for a complete installation on a stock Mustang GT without additional parts.
• No Tune Required: Connects to OEM headers and the factory axle-back without modifying any sensor positions or requiring an ECU recalibration for normal street operation.
• 2015 to 2026 Mustang GT Compatibility: Fits S550 and S650 platforms including GT, GT Premium, Bullitt, Mach 1, and Dark Horse models running the 5.0L 4V Coyote V8.
• Weight Savings Over OEM: Eliminates the heavy factory resonator assembly, reducing total exhaust system weight.

What's Included

• 1 x Kooks 11513500 Stainless Steel OEM Resonator Delete H-Pipe
• 2.25 inch to 3 inch Mid-Pipe Adapter Set
• Band Clamps for All Connection Points
• Installation Instructions

Product Specifications

This Part Fits

Frequently Asked Questions

Q: Does this H-pipe fit the 2015 to 2017 Mustang GT or only 2018 and newer models?
A: This kit fits the full 2015 to 2026 5.0L 4V Coyote Mustang GT lineup. This includes 2015 through 2017 S550 models in addition to the 2018 to 2023 mid-cycle and 2024 to 2026 S650 generations. Verify your exact submodel against the fitment table above before ordering.

Q: Does the 11513500 fit the GT500, GT350, or Shelby models?
A: No. This H-pipe is designed specifically for the 5.0L 4V Coyote V8. The GT500 uses a supercharged 5.2L Predator, the GT350 and GT350R use a flat-plane 5.2L Voodoo V8, and Shelby 700-series cars use different exhaust routing. None of those applications are compatible with this part.

Q: Does installation require cutting the factory exhaust piping?
A: No cutting of the primary catalytic converter outlet pipes is required. This kit includes mid-pipe adapters and band clamps that connect to the OEM mid-pipe ends directly. The only removal required is unbolting the factory resonator from its hangers and disconnecting the OEM band clamps at the resonator inlet and outlet connections.

Q: Will a tune be required after installing this H-pipe?
A: No tune is required. This kit retains the factory catalytic converters upstream and connects to the OEM axle-back exhaust downstream. No oxygen sensor positions are changed and no ECU recalibration is needed for normal street operation.

Q: Is this resonator delete H-pipe street-legal?
A: This kit retains the factory catalytic converters, which keeps the system within 49-state EPA requirements. It is not CARB-approved and is not legal for installation on street-registered vehicles in California or other CARB-regulated states.

Q: Does this kit work with aftermarket long tube headers?
A: This H-pipe is designed to connect to OEM factory headers and the OEM mid-pipe. Compatibility with aftermarket long tube headers depends on the collector diameter and outlet style of the specific headers being used. Verify collector diameter and connection type before combining with aftermarket headers.

Q: How much louder will the exhaust be after installing this resonator delete?
A: Removing the factory resonator box noticeably deepens and enriches the exhaust tone at idle, cruise, and wide-open throttle. The change is significant but not as extreme as removing the mufflers. The result is a deeper, classic muscle car H-pipe sound rather than the harsh, raspy volume increase of a full muffler delete.

Q: What is the warranty on the Kooks 11513500?
A: Kooks provides a limited lifetime warranty on stainless steel components to the original purchaser. Under the Magnuson-Moss Warranty Act, installation of this part does not void your vehicle's factory powertrain warranty solely on the basis of the modification.

Q: Does this kit fit the 2024 to 2026 S650 Mustang GT and Dark Horse?
A: Yes. This kit is confirmed to fit the 2024 to 2026 S650-generation Mustang GT, GT Premium, Dark Horse, and Dark Horse Premium models running the 5.0L 4V Coyote V8. See the full fitment table above for the complete year, submodel, and engine breakdown.

Why Kooks

• Over 60 years of American-made exhaust excellence with documented NHRA, NASCAR, and SCCA race victories.
• Every Kooks exhaust component is TIG-welded and inspected before shipping from the Kooks USA facility.
• Limited lifetime warranty on stainless components backed by more than six decades of fabrication expertise.

Installation Instructions

1. Safely raise the vehicle on a lift or jack stands to provide clear access to the full mid-pipe and resonator section running between the factory catalytic converters and the axle-back mufflers. Ensure the exhaust system is completely cool before beginning work.
2. Loosen and remove the OEM band clamps connecting the factory resonator to the front mid-pipe sections behind the catalytic converters. Slide the clamps clear of the connection points.
3. Unbolt the rear exhaust hanger brackets at the subframe to release the factory resonator and rear exhaust section as a unit. Lower the assembly carefully to avoid damage to the fuel tank, driveshaft, or surrounding components.
4. Separate the factory axle-back muffler sections from the resonator. These will be reinstalled in conjunction with the new H-pipe. Inspect the OEM axle-back slip-fit connections and clean any corrosion from the pipe ends to ensure a leak-free fit with the included band clamps.
5. Slide the 2.25 inch to 3 inch adapter pieces included with the kit onto the rear of the mid-pipe sections. Position the included forward band clamps onto the adapter sleeves but do not tighten at this stage.
6. Fit the H-pipe into position, connecting the 3 inch inlet ends to the adapters and the 2.25 inch outlet ends to the factory axle-back muffler slip joints. Verify that the H-pipe hangs level, clears all chassis components, and aligns correctly with the axle-back inlet ends on both sides.
7. Reinstall the rear exhaust hanger bracket bolts to the subframe to support the system weight. With all components in their final position, begin tightening all band clamps starting at the front connection and working rearward. Tighten clamps firmly with a 15 mm socket but do not over-torque.
8. Start the vehicle and allow the exhaust to reach full operating temperature. Inspect all clamp joints for audible or visible exhaust leaks, and re-torque any loose connections after the first heat cycle.

California Proposition 65 Warning: This product can expose you to chemicals including Chromium and Nickel, which are known to the State of California to cause cancer, birth defects, or other reproductive harm. For more information go to www.P65Warnings.ca.gov.