I had a 91 firebird vert. I was looking to upgrade the sound system. The stock system sounds terrible. What is the stock size of the speakers in the back. I dont want to cut anything, just want to put better speakers back there that will mpount right in as a direct replacement.

Also as far as putting a sub in the tiny trunk. Wat have you gusy done with that? I almost feeel like its too far away and dont even make sense to do.

 

4x6

 

My '91 TA has 6.5 inch round speakers. I bought it new and have replaced them twice in its 20 year history. I think you should pull the panel they are mounted to and determine for yourself what you have. Pontiac or ASC may have used different types during production because I believe the mounting holes are custom cut in the panel.

The dimension that is most important is the depth. It is a really tight place and many speakers will not fit.

As for an amp, check out suggestions in the "AUDIO" forum. There are several ways to mount one and they make a big difference in sound quality while driving at highway speeds. I put mine in the luggage well next to a box with a 10" sub pointing up. Sounds good but not overpowering. I made a cover over the amp that fills in the well and creates a useful floor.

 

Infinity makes a 10 or 12 inch powered sub built in a suitcase type enclosure that would be perfect for the area where the spare tire goes or on the other side of the car same place. I like the kenwood amp KAC X501F. Very powerfull and extremely clean and 4 channel. I have used this set-up for years with infinity kappa speakers except for the sub but I want one soon. You can hear people take a breath of air just before they sing; extremely clear and clean.