I have sinks in them. With adequate venting, minimizing the wall thickness and turning a venturi type opening at the cone end, the T/S parameters did not change a bit, except for the better at higher power. My total surface area of the vent holes in the tube exceeds the actual vent size of the c. I love my C's, and as finances permit will probably relegate the a's to some other cab (Home theater) and buy another pair of c's for the PA subs.