NGK 97506 "2 Step Colder" Spark Plug - Turbo BMW MotorsThese NGK Laser Iridium replacement plugs are factory standard in BMW N20 & S55 engines and are suggested for most turbo BMW engine including the N54, N55, N63, N63TU, S63, and S63TU applications. They are 2 steps colder than stock N54 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". Beware of counterfeit NGK