We consider symport/antiport P systems using the time as the support for the output of a computation. We describe and study the properties of “timed symport/antiport systems”, showing that this new model of membrane systems based on time has more power/flexibility, and thus allows us to improve previous universality results. We were able to improve or match the best results concerning the symport/antiport systems which consider the output as originally defined as the number of molecules found in a pre-defined elementary membrane in the halting configuration of the system.