Preheat the oven to 375 degrees F.
In a mixing bowl combine the graham cracker crumbs, 1/4 cup sugar, and butter and mix until thoroughly combined. Using your hands, press the mixture firmly into a 9-inch pie pan, and bake until lightly browned, about 15 minutes. Remove from the oven and transfer to a wire rack to cool completely before filling.
Reduce the oven temperature to 325 degrees F.
In a non-reactive mixing bowl, combine the condensed milk, lime juice, and whole eggs. Whisk until smooth and thoroughly combined. Transfer the filling to the cooled pie shell. Bake for 15 minutes. Transfer to a wire rack to cool to room temperature, then refrigerate until thoroughly chilled, at least 2 hours.
Place the egg whites in a clean mixing bowl and beat on medium speed until the egg whites form soft peaks, about 2 to 3 minutes. Slowly add the remaining 1/4 cup sugar and beat until the whites form stiff, glossy peaks, another 1 to 2 minutes. Do not over mix or the whites will dry out.
Place the meringue in a piping bag fitted with a star tip and pipe the meringue onto the chilled key lime pie in dollops that run in concentric circles, completely covering the top of the pie. Use a blowtorch to caramelize the meringue and serve garnished with the candied lime peel.
Bring 4 cups sugar and the water to a boil in a 1-quart saucepan. Stir until the sugar dissolves and remove from the heat. Set aside.
Place the lime zest in a separate saucepan and cover with cold water. Bring to a boil, drain the zest, and rinse under cold running water. Repeat this process 2 more times, using fresh water each time.
Place the blanched zest in a saucepan and cover with enough of the sugar-water syrup to cover by 1-inch. Bring the syrup to a boil and reduce heat to a simmer. Cook the zest until it is tender and translucent in color, about 10 minutes. Remove from the heat, cool, and drain the zest. Lay strips of zest on a wire rack to cool, then toss in the sugar until well coated. Transfer to an airtight container and store at room temperature for up to 1 month.