allways use NGK here. the std jobbies are cheep and long lived and never had a problem with them they also take to modifyed engines well.
the better plugs in there range are defantly a lot better than others on the market ive tryed the iridium and raceing compotion plugs are bloody good. put a set of iridiums in a mates rally car and you can actualy drive it about round town without it fouling them and quite often on verry modifyed engines running methanol can usally coax a cold start out of them with it running plugs in, that saves a lot of ballache swaping plugs just to get the motors warmed up