Preheat oven to 325°F. For the Cake, sprinkle pecans evenly in bottom of greased and floured 12-cup Bundt pan. Mix cake mix, pudding mix, eggs, water, butter and 2 tablespoons rum flavor in large bowl with electric mixer on low speed 30 seconds. Beat on medium speed 4 minutes. Pour into prepared pan.
Bake 1 hour or until cake begins to pull away from sides of pan. Cool in pan 15 minutes.
Meanwhile, for the Glaze, mix sugar, butter and water in small saucepan. Stirring constantly, bring to boil on medium heat and boil 1 minute. Remove from heat. Stir in 1/2 teaspoon rum flavor. Invert cake onto serving platter. Pierce cake with fork. Spoon glaze over warm cake.