Fortify Shouts cannot be disenchanted from, or enchanted onto any item. The only known item that provides this effect is the Amulet of Talos. The Dragon Priest mask known as Morokei which is procured during the "The Staff of Magnus" was supposed to also have the fortify Shout enchantment but doesn't due to an improperly assigned enchantment, instead it merely increases Magicka regeneration by 100%.
Fortify Shouts is a blessing called the Blessing of Talos given by activating a Shrine of Talos. It can be stacked with the Amulet of Talos to produce an effect in which the time between shouts is decreased by 40%, which allows for more shouts to be cast.
The shout Dragon Aspect provides a 20% reduction in shout cool down time.