So I had a compression and leak down test performed in preparation to get tuned. I was told that my spark plugs are cross threaded and look like they need to be replaced. So I have been looking at spark plugs. I am wanting to get NGK Iridium spark plugs. I was just wondering as far as what heat range I would need. The car will be tuned with

air intake
o2 housing
full turbo back exhaust
walbro 255
and grimmspeed 3 port.

I contacted Rallysport Direct asking whether I should do stock heat range for those mods and a tune or whether I should go one step colder. They told me I should do one step colder spark plugs being that with those bolt ons and a tune I should be making 70-100whp more than stock. I was just looking to see whether I should go with stock heat range, or should do one step colder as I plan on modifying to full bolt ons later?

Thanks for the help, Lonnie.

 

Use stock plugs. You don't need one step colder plugs for those parts (even when you add more bolt on parts).

 

NGK ILFR7H are the stock IX plugs, just FYI for when you go to order