BOSE replacement
I replaced the BOSE system in my 87 convt. I had an amp or two go out and as you say they are expensive,I also wanted a CD.I installed a Pioneer model DEH-P77DH. It is a din and a half in width so it fills in the space in the dash without the use of spacers.It is a tight fit and doesnt allow the head unit to be removed from the car as it is designed to do but that is OK with me.I replaced the speakers in the car with Bostons.I added two speakers to the dash pad,car had four speakers to start with,replaced the speakers in the doors[left the BOSE amp assembly in the doors and mounted the new speakers in the old space] and mounted the rear speakers on the mounts from the factory[a little different in a convt. than a coupe]. I dont think four speakers in the front of the car is necessary,I think all I can hear is the speakers in the dash pad.If I were to do this again I would just place the speakers in the doors.I bought a stero cable for my model car that plugs into the cars dash harness so you dont have to cut the factory wiring and it gives you the leads you need. You will have to run new wires from the new radio to the speakers,the BOSE system uses an amp relay that works with each BOSE speaker amp and cant be reused. The Pioneer radio gives a world of options[maybe too many] and seems to work well in the car. I did not want to have to use an amp in the car[space,wiring] because of the six speakers and this radio allows for wiring differnt omhage/wattage[serial/parerall] to the front and rear channels. Depending on what kind of system you are looking for,you will have to run wire . Good Luck
