Can you hook up subwoofers and amp to a factory stereo in a 1998 Toyota Camry?
No, you can't. It does not have such cable at all.
Since the wires in a Toyota are all different colors, all you have to do is go to a car radio store and ask for a car stereo Toyota wiring harness. It will come with intructions but basically all you have to do is plug that thing into the cars factory harness and hook the stereo up. It worked for my Camry 1990