Even at stock, I would recommend one step colder. The benefit of protecting your engine from possible detonation is just too hard to pass up.
The ones we typically use are Denso ITV22's. Protege Garage has them for like ~$45/set shipped for free. Just make sure you check the gaps on them before you install. Also, they cannot be gapped like other plugs, you cannot leverage on the electrode to open up the gap. You must pull back on the arm itself.
Just tell your mechanic to "gap them at 30" and you'll be okay.
Just tell your mechanic to "gap them at 30" and you'll be okay.
the bigger the gap the more voltage required. When you make the gap bigger you do increase the amount of fuel and air that comes in contact with the spark which essentially makes the combustion easier. However, like anything, too much of anything is never a good thing and a gap that is too big can cause a condition where it is too easy to ignite.
Most vehicles won't see knock at a stock or close to stock level. If you're running a retuned vehicle (AP or Standback), then you are more likely to knock, as your boost targets may be higher....