Preheat oven to 350°F Lightly grease loaf pan or put liners in muffin pan.
In medium bowl, combine flour, baking soda and salt; set aside.
In large bowl, add 2 bananas and sugar. Whip for a good 3 minutes until light & fluffy. Add melted butter, eggs and vanilla; beat well scraping sides. Mix in dry ingredients until just blended. Mash other 2 bananas so they still have a bit of texture and fold into.
Pour batter into loaf pan or muffin cups.
Bake for 1 1/4 hours if in loaf pan. Approx 15-20 minute if large muffins. Check with toothpick.
Cool for 10 minutes then turn out loaf or pull muffins out of pan to cool completely. Dust with powdered sugar.