An exhaust valve assembly comprises a housing having a central axis. A ram assembly moves along a shaft fixed inside a hollow interior of the housing. Downstream movement of the ram assembly increases the size of the valve opening, allowing additional exhaust gases to pass through the interior of the housing. Springs maintain the ram assembly in a position in which exhaust gases may pass around the ram assembly. Sufficient force on the ram assembly from exhaust gases compresses at least one spring allowing the ram assembly to move downstream, thereby allowing additional exhaust gases to pass through the interior of the housing.