Rio Vista works pretty good, it makes my favorite color intensifying shampoos. I don't like Quic Black or any other shampoo from that line. I used it once on my horse and it dried his skin out, and didn't really do much for his color. Others I know who have used it have had the same problem. So I stick to Rio Vista.
I also have used the Rio Vista and love it. For whitening, I have used Orvus, which is great, but there is an easy quick one...I can't remember the name and it is packed away so it won't freeze-it is a spray on, in a white bottle.....found it! This: Dover Saddlery | Mane N' Tail Spray and White .
Great stuff for stockings!