When tuning your BMW N55, S55, S63TU it is recommended to go with 1-step colder spark plugs. We've found the NGK SILZKBR8D8S (97506) in the picture attached working great when gapped to appropriate spec. If you'll be running less than 25psi of boost we suggest a 0.020" gap, or 0.018" if planning to go higher. In most cases though we just go with the 0.018" gap and call it a day. 谷歌翻一下,0.018就是差不多0.5间隙额