Lightly spoon 1 1/3 cups flour into dry measuring cups; level with a knife. Combine with granulated sugar, baking powder, ginger, baking soda, and 1/4 teaspoon salt in a bowl. Combine yogurt and next 5 ingredients (yogurt through egg); add to flour mixture, stirring just until moist. Spoon batter into a 13 x 9-inch baking pan coated with cooking spray, spreading evenly.
Lightly spoon 3/4 cup flour into a dry measuring cup; level with a knife. Combine with brown sugar, cinnamon, and 1/4 teaspoon salt; cut in margarine and corn syrup with a pastry blender or 2 knives until mixture resembles coarse meal. Combine 1/2 cup streusel mixture and peaches in a bowl; arrange peach mixture evenly over batter. Sprinkle with remaining streusel mixture. Bake kuchen at 375° for 50 minutes or until a wooden pick inserted in center comes out clean. Cool on a wire rack.