Originally Posted by Jon Kerr

Quick nitro noob question. I run the #6 Ninja plug in my .21 buggy on 30% O'Donnell. It works great with no problems. But I hear about guys running a hotter or cooler plug for certain fuels and conditions. What plugs are hotter (higher number or lower number) and when would you change? What makes them different? Is it more or fewer coils? Like I said. The #6 is what I was told to run and it's been good. I just want to have a good understanding.