2003 for mustang, I am gonna get the factory Motorcraft plugs, but Does anyone know the # for one step colder than stock? I'd like to get a step colder to help with a slight Detonation problem I had when I maxed out the timing with 93 octane.......... Any help appreciated, thanks.

 

HERE

 

Thank you very much, I didn't even know that was there.

 

no prob