FOR THE 990 ONLY the 950 uses a different plug!

 Iridium IX® 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

• 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 - superior anti-corrosion and anti-seizing properties
  
• Outstanding acceleration, high fuel efficiency and durability
  
• Ultimate design, technology and performance.