A method of modulating the flow of fluid extrudate as it passes through one or more product cooling channels in an extrudate cooling die, said cooling die utilising the flow of a coolant through one or more coolant flow channels, from a coolant inlet point to a coolant outlet point, at least one of said coolant flow channels being located in thermal proximity to at least an associated one of said product cooling channels, to effect cooling of the extrudate from an extrudate inlet temperature to an extrudate outlet temperature.