Brass Buster you say? Yes this is the shampoo you need to be using if you are trying to eliminate some warm tones of yellow in your highlighted hair. This isn't just for blondes but also for brunettes with some highlights. This gives a cooler tone to your hair if that is what you're looking for. Think of the color wheel. What is on the opposite side of yellow? It's purple which when they meet they will neutralize each other and brighten the warm yellow tones down. I personall