possible audio upgrades for '89 90Q

["gsethi" <gsethi@corp.webtv.net>]

I was wondering if any listers who upgraded the stereo system had any advice
or suggestions before I upgrade the sound system.
 1. speakers? are non amplified replacement speakers the way to go if
replacing head unit.
2. would these non amp speakers fit and if so what kind?
3. getting good bass- with the location of the gas tank between trunk and
passngr compartment I was wondering what is the best avenue to approach
getting good bass.
4. possible amp location. If I go with an amp, is there a best location
Any other things I should know?

Thanks, Gurdev