In a small saucepan, combine 1 cup of the sugar, the water, both zests and both chilies. Bring to a boil, stirring occasionally, then remove from the heat and steep for 15 minutes. Strain into a jar, discarding the solids. Let cool.

While the syrup cools, in a small bowl, stir together the salt, chili powder and remaining sugar. Spread the mixture on a small plate. Use the orange wedge to moisten the rims of 2 rocks glasses, then dip in the chili salt, turning to coat.

In a cocktail shaker, combine the tequila, pineapple juice, lime juice and 1½ ounces (3 tablespoons) of the chili syrup. Add 2 cups of ice cubes and shake vigorously, 10 to 15 seconds. Strain into the prepared glasses.