I too want to improve my existing system but am not the least bit interested in shaking the emblems off of my VX or annoying the people next to me in traffic. It's for my listening pleasure, not theirs. Besides, I'm to old for that S@#T!

Have been talking to a local audio shop owner about this, and he said I would be amazed how well my existing speakers (there not blown or rattling) would sound with just some simple amplification. We also talked about adding a 6 inch woofer built into the spare tire area strapped to the spare with its own enclosure.

I'm thinking 3 smallish amps with an active 3-way crossover. Placement won't be an issue since I plan on removing the rear seat and using the space more effectively

Maybe a little sound damping to knock down some of the road noise.

The 3 sites suggested by biju look well worth bookmarking and here is another that will give you just a brief outline of the different components.

http://www.carstereos101.com/

Good luck and good listening