The kinetic energy of the mass of exhaust gas carries it along the exhaust pipe, and causes a pressure build up ahead of the mass of gas and a partial vacuum behind it. This principle is used in a tuned exhaust system.
Culligan - $2352 ($2053 w/o R/O unit) Culligan Gold Series (10), Good Water Machine. If I were to look at price only, I would go with either the cheaper Ecowater system w/R/O at $2698 or the Culligan system. At almost $4k, the Kinetico system seems greatly over priced.
Soft water will also improve water heater efficiency and leave no water spots on glassware in the dishwasher. A water softener company will charge $915 to install a good quality water softener system for a small house with one and a half bathrooms. If you have plumbing experience and tools, you can buy the unit and the installation kit for $495, the water softener installation cost, and save 45 percent. Carefully read the directions before deciding whether to install it yourself so that you understand everything that's involved.