Preheat the oven to 425°F. Line a 12-cup muffin pan with cupcake liners or spray with non-stick cooking spray.
Sift together flour, salt, and baking powder in a small bowl and set aside.
In a large mixing bowl beat or whisk together eggs, melted butter, sugar, vanilla extract, milk, and peach juice.
Dump dry ingredients into the egg/milk mixture and stir gently, just until combined. Do not overmix.
Drain peaches (be sure you have added 2 tablespoons of the juice to the batter before discarding -- see above).
Dice peaches into very small pieces (large chunks will weigh down the batter and add too much moisture).
Toss 1 cup of diced peaches with 1 tablespoon of flour and fold into the muffin batter.
Divide batter between the 12 muffin cups in the prepared pan, filling each cavity about ¾ of the way full.
Sprinkle a few pieces of diced peaches over the top of the muffins.
Prepare the streusel by combining flour, sugar, and cold cubed butter in a small bowl. Use a fork or pastry blender to cut in the butter until the mixture forms a crumble.
Sprinkle streusel over the tops of the muffins.
Bake at 425 °F for 6 minutes. Turn down the heat to 350°F and continue baking for 15 to 18 minutes more until a toothpick inserted in the center of the muffins comes out clean.
Cool muffins in pan for 5 minutes. Remove muffins to a cooling rack to finish cooling.