NGK Iridium plugs

I put a set of NGK Iridium plugs in the scort yesterday....I´m not really sure if they are alot better than the regular NGK plugs I use because of the mileage ont he old ones...but it does have some extra pep to it....time will tell....maybe I´ll get another set of the ones I usually run and change them out at a track or if I can find one locally a dyno