So I've been reading on here a bit and found out I do have premium sound cassette . Door speakers and amp under the pass seat . So all speakers are 6ohm except the dash which are 3.5 . Are there any upgrades for the speakers . They don't sound bad , no cracking or weird noises or anything . But I would like to get better sound . I did read "Installation of OEM 1993 Premium sound stereo into 87-92 Mustang " on here and great info . I had already wanted to get the cd slave to add on which are easier to find and am glad to know there is a difference in the face plates . Round vs square which my car has . There is a cassette /equalizer on ebay for $117 which would be cool too .