Preheat oven to 350.
Spray 9x13 baking dish with non-stick spray.
Make streusel: mix 1 c brown sugar, 1/2 c granulated sugar, 1/2 tsp salt and 1 tsp cinnamon, 1 c butter and 2 1/2 cups of flour. Mix until well combined.
Add remaining flour, baking soda, baking powder, cinnamon, and salt to a large mixing bowl. Mix.
Add sugars and butter to a medium mixing bowl and beat with a mixer.
Beat in the eggs. Beat in the pumpkin puree.
Add the pumpkin mixture to the flour mixture and stir until combined.
Spread cake mixture into the pan.
Top with the streusel topping by crumbling it over the cake batter with your hands. The more the better.
Bake for 45 minutes or until a toothpick comes out mostly clean.
Cool completely before serving.