Preheat oven to 325°F Line a 12-cup muffin pan with paper or foil liners.
In a medium bowl, sift together flour, baking powder, and salt. In a measuring cup, combine Mt. Dew and concentrated orange juice.
Combine butter, sugar, and zest in a large bowl. With a hand mixer on medium-high speed, beat until fluffy. Add eggs one at a time, mixing well after each. Scrape the sides of the bowl before adding flour.
Add dry mixture in 3 additions, alternating with the wet in 2 additions, beating on low speed until just combined.
Pour batter into cupcake papers about 2/3 full. Bake for 16-18 minutes, or until a toothpick inserted in the center comes out clean. Cool on wire racks.
For the frosting:
In a saucepan, bring 1 cup of Mt. Dew to a boil over medium-high heat. Reduce heat until it no longer bubbles.
Let Mt. Dew evaporate for about 15 minutes. It should reduce by 3/4. You should end up with between 2 tablespoons and 1/4 cup of syrup. Pour it in a small glass measuring cup to cool.
Sift the confectioners' sugar into a mixing bowl. Add butter and beat, gradually increasing speed to high, until combined. Pour in heavy cream and Mt. Dew syrup. Continue mixing on high until fluffy. Add OJ concentrate, zest (and food coloring if you like). Mix on low speed until combined.