I have high density thin hair that is naturally curly. For the past 4 years i have been permanently straightening it once a year. This past year however, my hair has been very dry, and as recommended by my hairdresser, i switched to a sulfate free shampoo & conditioner.
To my surprise, i found that the roots of my hair that has grown out is EXTREMELY curly, and although the bottom half is straight which results in a slightly ridiculous look, the curls look great (I plan on going back to curly hair because of this product). And my hair is not as dry and has less split-ends.
This product is harsh chemicals free. This also means that it doesn't foam up as much, which takes some getting use to, but my hair/scalp feels clean and smells great! This product sells for about $30 for a large bottle, but you can get it at Winners or Marshall's for about $14.