Preheat oven to 350. In a large mixing bowl, combine flour, sugar, pumpkin spice, baking soda, and salt. Mix well.  Set aside.  Add eggs to a stand mixer. Beat for 2 minutes. Add in pumpkin and oil. Mix until combined. Add dry ingredients, mix until just combined. Fold in apples. Spoon batter into lightly greased or paper-lined muffin tins. Fill about 3/4 full. Meanwhile, combine flour, sugar, and cinnamon for streusel in a small mixing bowl. Cut in butter until crumbly. Sprinkle streusel on top over muffins. Bake for 30 minutes or until a toothpick inserted into the center comes out clean.