an extrusion apparatus for extruding thermoplastic material includes first and second die body portions that define a manifold which has a back line and is in fluid communication with an outlet through which the thermoplastic material is extruded and wherein the back line is substantially parallel to the outlet . first and second body bolts join the first and second die body portions together . the first and second body bolts are disposed at first and second equal distances , respectively , from the back line and are further disposed on opposite sides of a centerline of the extrusion apparatus at third and fourth unequal distances therefrom , respectively , and are substantially equally spaced from the outlet .