In a saucepan, combine sugar and water. Over medium heat, bring to a simmer, stirring regularly, until sugar is dissolved and syrup is clear and no longer cloudy. Remove from heat and allow to cool completely.
Slice mangoes and scoop flesh, discarding pit and skin.
In a blender or food processor, process mango until smooth and well-blended.
In a pitcher, combine mango pulp and simple syrup. Stir until combined and refrigerate to chill.
Serve in glasses over ice.
For the best results, use Ataulfo or Manila mangoes which have a sweet mango taste and velvety, less fibrous texture.