I plan no going FI next year. I was planning on buying some plugs and was wondering if it was alright to run 1 step colder plugs on a NA car. Just don't want to buy new plugs next year and have to switch them out. Or I guess I just could want till next year.

 

Bad idea, just run the spark plugs that are in the car until you are ready to buy the colder spark plugs for FI.

 

Run the LFR5A11 copper plugs --I had a set and just changed for no other reason to JUST change ---after 35,000 they were Gnats *** and mileage was 26 Plus---Nice color and almost 0 wear---I ran the Copper 5s with my Vortech. If you Turbo ---do the Copper 6s and do Plat if you like color---

Heat Range is Heat Range pretty much and Plug color is best on a Copper

Dial in before you go Iridium...they tend to be a little Snappy---and just no sense to it IMO

 

I'm running the "cold type" PLFR6A-11, no problems on the street or at the track, in central texas weather (down to around 33 degrees, not much colder than that).

According to the 2003 350Z service manual, you can run one step colder, from page MA-20:

Make NGK
Standard type PLFR5A-11
Hot type PLFR4A-11
Cold type PLFR6A-11