Heat the oven to 350 degrees. Line 24 regular muffin cups with paper liners. In a large bowl, combine cake mix, oil, egg whites, 1 cup sour cream, water, and 1 teaspoon coconut extract. Beat with an electric mixer on low speed until moistened. Beat on medium speed for 2 minutes, scraping the sides of the bowl if necessary. Stir in the coconut. Spoon evenly in the muffin cups, filling about 2/3 full. Bake for 15 to 20 minutes or until a toothpick inserted in the center comes out clean. If baking 2 pans at a time, switch positions halfway through baking. Cool in the pans for 5 minutes and then remove to cooling racks. Cool completely (about 20 minutes). In a medium bowl, combine the powdered sugar, butter, 1/3 cup sour cream and 1 teaspoon coconut extract. Beat with an electric mixer on low speed until moistened. Beat on medium speed until smooth and creamy. If the mixture is too stiff to spread, stir in 1 to 2 teaspoons of additional sour cream. Spread over the cupcakes. Sprinkle and press the remaining 1 ¼ cups coconut over the frosting. Decorate as desired right before serving. Store covered in the refrigerator.