Maximum Flow, Full Emissions Compliance: Long Tube Power Without the Compromise
The Kooks 1371H420 1-7/8-inch Header and Catted Connection Kit transforms the 2021 and 2025 Ford F-150 5.0L Coyote V8 by replacing restrictive factory manifolds with long-tube headers and high-flow catted Y-pipes that unlock over 60 horsepower and 50 lb-ft of torque to the rear wheels, while preserving emissions compliance for daily driving.
Handcrafted from T304 aircraft-quality stainless steel, the equal-length primaries and merged collectors optimize exhaust scavenging across the full RPM range, delivering crisp throttle response and a deep, aggressive exhaust note without drone on the highway.
The 3-inch catted connection pipes integrate seamlessly with the OEM mid-section, supporting up to 850 HP for tuned trucks or heavy towing, and feature precision laser-cut 3/8-inch flanges to eliminate warping under heat cycles. For F-150 owners seeking a bolt-on upgrade that balances power gains, sound refinement, and legal street use, this kit provides the engineered path to maximize the Coyote’s potential in work, play, or track scenarios.
Key Features
- 1-7/8-inch Long-Tube Headers: Equal-length primaries with merged collectors for maximum scavenging and mid-range torque.
- 3-inch Catted Y-Pipe: High-flow stainless catalytic converters rated for 850+ HP with quick light-off and sustained efficiency.
- T304 Stainless Steel Build: Aircraft-grade material with full penetration welds for corrosion resistance and lifelong durability.
- Laser-Cut Flanges: 3/8-inch thick stainless flanges, hand-ground ports to prevent exhaust restriction.
- Direct OEM Integration: Bolts to factory exhaust without cutting or welding; maintains OBD-II readiness.
- Power and Sound Gains: Dyno-tested for 60+ HP/50+ lb-ft increases with improved throttle feel and V8 rumble.
Product Notes
- 49-state EPA compliant not legal for sale or use in California or CARB states without exemption.
- Excludes F-150 Tremor models due to unique frame and exhaust routing.
- O2 sensor relocation may require extensions (included) ECU reflash recommended for tuned applications.
- California Proposition 65: Contains chemicals known to the State of California to cause cancer or reproductive harm.
Warranty: Limited lifetime to original purchaser on materials and construction.
Installation Notes
- Professional installation recommended requires exhaust lift or jack stands for access.
- Remove stock manifolds and Y-pipe bolt headers to cylinder heads using provided hardware.
- Torque flanges to 25-30 ft-lbs in sequence connect Y-pipe to OEM section and secure hangers.
- Perform O2 sensor installation and drive cycle for ECU adaptation check for leaks after heat-up.
This Part Fits
| Year | Make | Model | Submodel/Engine |
|---|---|---|---|
| 2021 and 2025 | Ford | F-150 | XL, XLT, Lariat 5.0L Coyote V8 (4V) |
| 2021 and 2025 | Ford | F-150 | King Ranch, Platinum 5.0L Coyote V8 (4V) |
| 2021 and 2025 | Ford | F-150 | Limited 5.0L Coyote V8 (4V) |
Note: Fits standard cab, super cab, and super crew configurations with 5.0L V8. Excludes Tremor, Raptor, and hybrid variants.
What’s Included in the Purchase
- (2) 1-7/8-inch Long-Tube Stainless Steel Headers
- (1) 3-inch Catted Stainless Steel Y-Pipe Connection
- Gaskets, Bolts, and Hardware Kit for Headers and Connections
- Oxygen Sensor Extensions and Bung Plugs
- Hanger and Clamp Kit for Secure Fitment
- Detailed Installation Instructions with Torque Specs
Total Package Weight: 65 lbs | Shipping Dimensions: 48″ L x 24″ W x 18″ H (crated for freight shipment)
Why Choose Kooks?
- Over 60 years of exhaust engineering, with wins in NHRA, NASCAR, and SCCA competitions.
- Handcrafted in the USA using T304 aircraft-quality stainless steel for precision and strength.
- Limited lifetime warranty and dyno-proven for reliable power delivery.
Frequently Asked Questions
- Q: Is this kit legal in California?
A: No, 49-state EPA compliant only CARB EO required for California use. - Q: Will this fit my 2024 F-150 Lariat 5.0L?
A: Yes, direct bolt-on for all non-Tremor 5.0L models from 2021 through 2025. - Q: What power gains can I expect?
A: Dyno results show 60+ HP and 50+ lb-ft to the wheels, with further gains from tuning. - Do Kooks headers require a tune after installation?
Yes. A professional tune is strongly recommended after installing long tube headers. The significant improvement in exhaust flow changes air fuel ratios and requires ECM recalibration to achieve optimal power output and safe operation. - Will these headers void my factory powertrain warranty?
Under the Magnuson-Moss Warranty Act, a manufacturer cannot void your vehicle warranty simply because you installed an aftermarket part unless they prove the component directly caused the failure. Consult your dealer for specifics on your situation. - Q: Do these Kooks headers require a tune after installation?
A: Yes. A professional tune is strongly recommended after installing long tube headers. The significant improvement in exhaust flow changes air fuel ratios and requires ECM recalibration to achieve optimal power output and safe operation. - Q: Will Kooks headers void my factory powertrain warranty?
A: Under the Magnuson-Moss Warranty Act, a manufacturer cannot void your vehicle warranty simply because you installed an aftermarket part unless they prove the component directly caused the failure in question. Consult your dealer for specifics. - Q: What warranty does Kooks provide?
A: Kooks products are backed by a limited lifetime warranty to the original purchaser against defects in materials and workmanship. Racing and competition use applications may have specific warranty exclusions. Contact Kooks Performance directly for warranty details.
Shipping & Handling
- Availability: Ships within 1-2 business days.
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