A method and apparatus for providing an evenly mixed additive enhanced gypsum slurry to a web. Calcined gypsum and water are inserted into a mixer through at least one inlet of the mixer. The contents are agitated to form a slurry. The slurry is passed from an outlet of the mixer into a conduit. An additive is introduced into the slurry along a length of the conduit to achieve a flow stream of a slurry/additive mixture. A cross section of the flow stream is expanded in the conduit while not changing direction of the flow stream and a direction of the flow stream is changed while not expanding the cross section of the flow stream and conduit, all prior to the flow steam exiting from an outlet of the conduit.