I found NAK Nourishing shampoo and conditioner combo excellent, but I had to wash my hair too often due to it looking greasy. When you are wearing hair extensions, the less you wash your hair the better. Once or twice a week is sufficient. This product gets a thumbs up from me and would be my first choice if my hair ever became unhealthy.
TIP: A good idea if you don’t want to wash your whole head of extensions then wash your fringe/bangs or the front of your hair as well as a portion at the top. This can give you back your shine without going to the trouble of washing and drying a whole head of extensions. I recommend NAK Nourishing hair shampoo and conditioner if your hair is dry and brittle. Extensions have a habit of being a bit dry due to the fact that they no longer have a follicle so a good nourishing shampoo and conditioner is essential.