I need new spark plugs and i wanted to know the difference between them. I have seen some people with +2 hotter or colder what does it mean. I want the best possible plugs. Im thinking about denso iridium. My car is na right now. I have exaust, intake filter, intake manifold, igntion wires, vafc II. I am getting a fuel pressure regulator, fuel rail, nology ignition wires, venom performance module, ground kit, racing pullies in the next week. These are the mods that actually make a difference in my car im pretty sure...cuz i have a stage 3 clutch and 8.9 pound flywheel, etc. blah blah blah but i doubt any of those would make a difference on what plugs i use. Please someone help me. Last but not least, how much do they cost and where can i get em. Thanks.

 

Look up "heat range". The more power you're making, the colder you need the plugs to be to prevent detonation.