Cook 4 slices bacon till crisp. Remove bacon, reserving about 3 Tablespoon drippings in skillet. Drain and crumble bacon; set aside. Cook half cup chopped onion in reserved drippings till tender. Stir in two 16-ounce cans pork and beans in tomato sauce, 2 Tablespoon brown sugar, 2 Tablespoon catsup, 1 Tablespoon Worcestershire sauce, and 1 Tablespoon prepared mustard. Turn into a 1.5 quart casserole. Bake, uncovered, in a 350 degree oven for 1.5 to 1.75 hours, or cook in the microwave oven on HI for 10 to dozen minutes. Stir half way through cooking time, Top with bacon. Let stand a few minutes before serving.