sparkplug

Hey guys! I've got a few questions to start with and potentially more to follow. I have 1995 GTX thats been in my family since it was purchased new. It just got a remanufactured SBT engine that I installed, as well as the carbs rebuilt, which I also did. Took them to a semi-local shop to...

OK, the 2005 3d is an easy upgrade The OEM Plug is BR8ES, and the upgraded one is BR8EIX But on the 2006 DI the OEM is ZFR4F-11, and NGK doesnt have the iridium upgrade option, but a website mentioned that ZFR5FIX-11 is the equivlent. However, its one degree colder. Are these numbers...