NGK R2556G-9- These are the best heat range 9 plugs you'll ever run period! This is a plug you spend a little more on when you want the best and want to have the lowest risk of a plug failure. The HKS M45XL have nothing on these!

NGK R2556G-10- These are the best heat range 10 plugs you'll ever run period! This is a plug you run in cars making BIG power creating a lot of boost and heat! Not many street driven cars will even need these. These would be considered on cars making 3x OEM power or more!

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