BMW NGK 97506 Spark Plug For N55, S55, N63 And S63 EnginesNGK Laser Iridium replacement plugs for BMW N55, S55, N63, and S63 engines. They are one step colder than N55 plugs and factory S55 plugs and suggested for higher boost E85, water meth injection, and or upgraded turbocharger applications across all late model turbo BMW models. We suggest setting the gap down to 0. 020", or 0. 022 if running a stage 2 map on the N55 engine. PRODUCT SPECIFICATION Genuine NGK Laser Iridium Spark Plug 1 Step colder than