Prepare crust: Heat oven to 375 degrees.In 9" pie plate combine graham cracker crumbs and 2 tbsp. sugar;stir in butter until blended. Press mixture firmly and evenly over bottom and sides of pie plate; bake 10 minutes until browned.Cool completely on wire rack. Prepare filling: In top of double boiler using wire whisk,beat egg yolks,lime juice,1/3 cup sugar and salt until well blended.Set over simmering water;cook about 5 minutes,stirring constantly until mixture is thick enough to coat back of metal spoon.Remove from heat; stir in 1 tbsp. grated lime peel.Refrigerate mixture about 45 minutes until cool.Meanwhile,in large bowl with electric mixer at medium speed,beat cream until soft peaks form.Set 1 cup whipped cream aside for garnish;fold cooled lime mixture into remaining cream.Spoon filling into prepared crust;refrigerate at least 2 hours until set. To serve: Spoon remaining whipped cream decoratively over top of pie; sprinkle cream with remaining 1 tbsp. lime peel.Garnish with lime slices,if desired.Makes 8 servings.