Can you install a stereo and sub woofer in a 323 1989 Mazda?

yes, easily...you will need a new head unit though. if you want a sub you will need a head unit with RCA outputs to connect the ammplifier. i run a panasonic head unit, 1200w amp, 2 12" subs, 4 mids and 2 tweeters in my 89' familia