lookin to buy a set fo ngk plugs for the evo what would the diffrence be between "regular plugs" and " one step colder "

 

Colder plugs are usually used when you have a significant amount of mods and horsepower over stock. It helps against predetenotation. However if your car is stock it will not help it at all and may not even run right because the spark does not get hot enough. If you do a search you will find many posts about spark plugs.

 

As I've posted in more detail in some of those threads that would have come up in a search, even if you don't go colder, I now see no reason not to go with a non-projected 7 range plug as cheap insurance (BR7ES).