Preheat oven to 350 F. In a large bowl, combine the flour, sugar, pumpkin pie spice, baking soda and salt. Combine eggs, pumpkin and oil; stir into dry ingredients until just moistened. Fold in apples. Fill greased or paper-lined muffin cups 3/4 full. For topping, combine sugar, flour and cinnamon. Cut in butter until mixture resembles coarse crumbs; sprinkle 1 teaspoon over each muffin. Bake at 350 F for 30-35 minutes or until muffins test done. Cool in the pan for 10 minutes before transferring to a wire rack. This recipe makes about 1 and 1/2 dozen muffins.