O.S. P3 turbo A3 regular. Those are the only plugs I use. The Odonnells are ok too but you could not give me a Novarossi(dont light all the way to the bottom ) or Mccoy(unpredictable lifespan somewhere between 5 and 10 minutes ) plug. I run two plus 4 novas, one with turbo button and one without. The O.S. plugs give me two full race days + with no issues.