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NGK Iridium IX LTR6IX-11 Spark Plugs (Set of 16) (03-08 5.7L, 06-10 6.1L, 11+ 6.4L) - 6509

Product Code: 6509
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The Spark Plug Serious Enthusiasts Rely On.

Designed specifically for the performance enthusiast. Iridium IX offers extreme ignitability, improved throttle response and superior anti-fouling. NGK iridium plugs represent the ultimate evolution of spark plug technology and performance. The iridium center electrode is both stronger and harder than platinum. This allows NGK engineers to design an ultra-fine (0.6mm) center electrode reducing the voltage requirement for spark. This allows for a brighter, stronger spark from your existing ignition system. The ground electrode has a tapered cut at the firing end which reduces quenching for better flame core growth and increased ignitability. The combination of fine wire center electrode and tapered cut ground will increase performance, improve acceleration, and fuel efficiency.

Fine Iridium tip ensures high durability and a consistently stable spark. Iridium alloy has extremely high melting point, perfect for today's high-tech, high-performance engines.

"Trivalent Metal Plating" has superior anti-corrosion and anti-seizing properties.

Outstanding acceleration, high fuel efficiency and durability.

Ultimate design, technology and performance.


  • Resistor: Yes
  • Manufacturer Heat Range: 6
  • Electrode Core Material: Copper
  • Electrode Tip Material: Iridium
  • Insulator Type: Projected
  • Spark Plug Thread Size: 14mm
  • Spark Plug Reach: 25mm
  • Spark Plug Seat Style: Tapered
  • Wrench Diameter: 5/8 in. 
  • NGK Part Number: LTR6IX-11