A valve assembly for a high-pressure fluid pump is described herein. The valve assembly includes a valve seat disposed in a cylindrical bore in a fluid end of the pump, and a valve body that includes: a top plate defining at least one pressure window, a lower sealing surface disposed below the top plate, and a dampener disk disposed between the top plate and the lower sealing surface, the dampener disk configured to expand in response to pressure exerted thereon via the top plate and through the at least one pressure window.