Preheat over to 300 degrees. Remove thin membrane from the back of ribs by slicing into ribs with a knife and pulling the membrane off with paper towels. Combine salt, garlic powder, and pepper; rub all over the meaty side of ribs. Cut racks in half, if desired. Arrange ribs in a large roasting pan. Cover tightly with foil. Bake 3 hours or until very tender. Uncover and cool 15 minutes. Drain. Preheat grill to medium-high. Place ribs, meaty side up, on covered grill lid, 10 minutes. Baste and grill 5 to 10 minutes longer or until sauce clings to ribs.