BA Audio Related - HELP NEEDED!

[BAMKII]

Hello all, I am new to this in more ways than one. I have just bought a mk2 ba falcon, it is the first ford I have ever owned, I have previously had 4 commodores, and I usually frequent the holden related forums. I need some advice re; BA Sound system. My last car was a VS commodore, and it was pretty easy to replace head units, speakers, wire up amps etc. and I had no fear in doing any of the above, but this falcon I have, is a different ball game. I have an awesome pioneer sound system that I pulled from my vs before I traded it in, but it seems, after having read some of the audio related posts on this site, that it will be useless. I have the standard audio, and it is bloody terrible! The speakers are weak, the sound is sub-standard, most cd-rs are a problem, overall - tinny would be the word. What are the options? I don't want to alter the factory look of the car too much. I am not fussed about the screen or ability to play dvds etc. MP3 is desirable, as the pioneer unit I have sitting here collecting dust is mp3 compatible. I like the steering wheel controls. Can you add an amplifier? Is it difficult to replace the speakers, what sizes etc. are they? Any advice would be greatly appreciated. Cheers