Preheat oven to 350°F.
Grease and flour 10-inch tube pan.
Reserve 2 tablespoons cake mix.
Combine remaining cake mix, pumpkin, sour cream, eggs, sugar, water and 1-½ teaspoons pumpkin pie spice in large bowl
.Beat at low speed with electric mixer until moistened.
Beat at medium speed 2 minutes
.Pour into pan. In small bowl, combine reserved cake mix, brown sugar and remaining ½ teaspoon pie spice.
Sprinkle on top of batter. .
Bake 50 to 60 minutes or until toothpick inserted in center comes out clean
Cool in pan 25 minutes. Invert onto cooling rack.
Turn right side up.Cool completely