A relief valve assembly is provided for use in connection with high pressure and ultrahigh pressure pumps. The relief valve assembly includes a valve pin having an engagement portion with a tapered surface and a valve seat having a valve pin receiving aperture defining a tapered surface on the valve seat to sealingly mate with the engagement portion of the valve pin when the valve pin is seated against the valve seat in a seated configuration. The valve seat further includes at least one bypass passage that extends from the valve pin receiving aperture to an exterior surface of the valve seat such that when the valve pin is displaced away from the seated configuration fluid can pass through the bypass passage and an annular space created between the engagement portion of the valve pin and the valve seat. Systems incorporating the relief valve assembly are also provided.