i have an 84 se. it does not have a factory sub, but i think i am going to buy one from the fiero store, are these factory subs hard to install under the dash? are they any good? The reason i am interested in this i don't want a whole lot of bass and don't want to loss leg room. I hope someone can help.

Have you considered an 8" or 10" in the center console?

If I am thinking right the 84 didnt have room under the dash for the factory sub. I know that 84 is a different beast. You might want to go to the pass side and go by the footwell light and see if there is any room before hand. I don't know how you'd wire it either. The factory car had an amp with the wiring and a control on the over head light piece. So that's another thought. You can run your own amp and sub and save some money.
Matt J
88 GT factory sub
88 coupe
87 GT 3.4
86 SE factory sub installed