Product review (5 stars): Works!
I found this product to work as advertised.  Our dishes were coming out cloudy at best, at times worse than they went in.  San Diego water.  So we gave the Dishwasher Filtration System from Difi  a try.  Installation was a bit more cumbersome than I would have liked, but I'm not much of a handyman.  It leaked out the top a bit, and maybe out the inlets/outlets, but after some tightning down of things, no leaks.
Results of my first wash after installation were pretty dramatically good!  Problem solved.  Quite happy with it for a few months, forgot about it, then dishes started coming out cloudy again.  Figured it was time for a filter replacement.  That didn't go as smooth as I'd like either.  In fact, I couldn't unscrew the top the first time I got under there and tried.  So I planned to pull it out and stick it in a vise on the weekend, but when I came back and gave it another try, it unscrewed nicely.  Anyways, replaced the filter, ran one wash with a dishwasher cleaner (Glisten), and then tried a new batch of dishes - dramatic improvement; excellent results again - sparkling clean glasses.  Don't know what else to say.  I highly recommend this product.