Preheat oven to 350 degrees. Spray two regular size muffin pans with non stick cooking spray and line muffin pan with paper muffin liners.

In a medium sized bowl, combine flour, sugar, pumpkin pie spice, baking powder and salt and whisk together. 

In a small bowl, add eggs and beat lightly. Then stir in pumpkin and vegetable oil. Add wet ingredients to dry ingredients and stir just until combined. Fold in diced apples. 

Use a standard sized ice cream scoop to measure muffin batter into lined muffin tins. 

In a small bowl, combine ingredients for streusel topping and divide evenly over muffin batter. Bake at 350 degrees for about 30 minutes, or until muffins spring back lightly to the touch. Let cool slightly and serve.