Kooks Ford 5.0L 4V Coyote Engine Stage 8 Locking Header Bolt Kit (10mm x 150 Coarse Thread)

USA Hand Built Performance Headers Proven on the Dyno and the Strip

The Kooks BK109 Stage 8 Locking Header Bolt Kit provides a reliable fastening solution for header installations on Ford's high-performance modular V8 engines, preventing bolt loosening and exhaust leaks caused by intense vibration and thermal expansion in 5.0L Coyote, 5.2L Voodoo, and 6.2L supercharged applications.

Made from high-strength stainless steel with an integrated locking mechanism, these M10 x 1.25 x 25mm fine-thread bolts maintain secure clamping force across 16 ports, ensuring headers remain sealed under boost pressures exceeding 20 PSI or track-level RPMs.

Unlike standard hardware that requires frequent retorqueing, this kit's design delivers consistent performance for tuned setups pushing 800+ horsepower, making it essential for Mustang GT, Shelby GT350, F-150 Raptor, and F-250 Super Duty owners upgrading to long-tube systems. The direct replacement for lost or damaged bolts in Kooks header kits integrates seamlessly, supporting daily drives, drag racing, or towing without compromising integrity.

Key Features

• Stainless Steel Material: Resists corrosion and endures exhaust gas temperatures over 1,500°F without fatigue.
• Stage 8 Locking Technology: Built-in locking feature counters vibration-induced rotation for long-term security.
• M10 x 1.25 x 25mm Fine Thread: Precision sizing matches Coyote, Voodoo, and 6.2L cylinder head ports exactly.
• 16-Bolt Set: Full coverage for both banks on V8 engines, with hex heads for easy wrench access.
• High-Strength Construction: Rated for repeated torque cycles up to 30 ft-lbs without stripping.
• Replacement Compatibility: Fits all Kooks headers for listed engines no modifications needed.

Product Notes

• Order only as replacement for damaged or lost bolts included standard with Kooks header kits.
• Fine thread specific to 2015+ Coyote/Voodoo and 6.2L supercharged heads use BK108 for coarse thread pre-2015.
• California Proposition 65: Contains chemicals known to the State of California to cause cancer or reproductive harm.
• Not for use on non-Ford modular V8s verify thread pitch on aftermarket heads.

Warranty: Limited lifetime to original purchaser against defects in materials or workmanship.

Installation Notes

• Clean port threads thoroughly to avoid cross-threading apply anti-seize for future serviceability.
• Torque in a crisscross pattern to 25-30 ft-lbs recheck after 100 miles or first heat cycle.
• Compatible with standard 13mm/16mm sockets no special tools required.
• Professional header install recommended bolt time adds 15-20 minutes to process.

This Part Fits

Note: Fits fine-thread cylinder heads on 2015+ 5.0L/5.2L and all 6.2L supercharged Ford modular V8s. Confirm head type for pre-2015 applications.

What's Included in the Purchase

• (16) M10 x 1.25 x 25mm Stainless Steel Locking Header Bolts
• Associated Locking Hardware (Washers and Inserts)
• Part Number: Kooks BK109

Why Choose Kooks?

• Over 60 years of exhaust engineering, with victories in NHRA, NASCAR, and SCCA events.
• Handcrafted in the USA from premium stainless steel for precision and reliability.
• Limited lifetime warranty and expert support for all installations.

Frequently Asked Questions

• Q: Does this kit fit my 2014 Mustang GT 5.0L?
  A: No, 2011 through 2014 Coyote uses coarse thread select BK108. BK109 is for 2015+ fine thread.
• Q: What torque should I apply?
  A: 25-30 ft-lbs in stages, using a calibrated torque wrench for even clamping.
• Q: Are these bolts reusable?
  A: Yes, the locking mechanism allows multiple installations without performance loss.
• 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

• Method: Standard ground UPS/FedEx.
• Availability: In stock and ships within 1-2 business days.
• Packaging: Secure pouch in a reinforced box to safeguard threads.