Preheat the oven to 350 degrees F (175 degrees C). Lightly grease 16 standard muffin cups or line with paper liners.

Make the muffins: Beat sugar, oil, and eggs in a bowl with an electric mixer on medium speed until creamy.

Mix flour, cinnamon, baking soda, and salt together in a large bowl. Gradually beat flour mixture into egg mixture until just combined. Fold in peaches. Spoon batter into the prepared muffin cups.

Make the streusel topping: Mix brown sugar, flour, butter, and cinnamon together in a bowl until crumbly. Sprinkle over muffin batter.

Bake in the preheated oven until a toothpick inserted in the center of a muffin comes out clean, 20 to 25 minutes. Remove from the oven and cool in the pan for 10 minutes before removing to a wire rack to cool completely.