Cook macaroni. In medium skillet, fry bacon until crisp. Drain and set aside. Saute onions, hamburger and salt. Drain excess fat. Add bacon, pork and beans, brown sugar, ketchup, Worcestershire sauce, mustard, and macaroni together and mix well. Pour into a 2 1/2 quart greased casserole dish.  Bake at 350 degrees for  45 minutes. If you prefer not to bake, just heat thoroughly and eat. I even like it cold.