Just wondering if you guys can help me out. I have a few general questions that I believe I have the correct answers to but would like you guys to check. I'm getting a smog check in a few days and concerned about my emissions.

lower or higher octane gas for reducing emissions? lower

advanced or retarded timing? a bit retarded

colder plugs or hotter plugs? a bit colder would help

I hope this is all correct but hopefully someone can correct me if I am wrong. Sorry this isn't ITR related but I trust technical advice from this forum a bit more.

Thanks!