When should timing belt be changed?

Hello, Change it. If this 21 year old sports car has never had the timing belt done, it needs it. If you have no record, it needs it. If I remember right, these are dual cam engines, both driven by the timing belt. In the event of timing belt failure, you will likely have to replace at least a couple bent rods. Good on you for asking, and the cool thing is that these are not that expensive to change like timing chains are. I would have this car in and out of the garage in about 2 hours. Let me know any questions you have, and here is a link if you would like shop recommendations: http://repairpal.com/mazda-within-10-miles-of-west-yarmouth-massachusetts-02673