ProtegeTech has an abundant amount of information on all generations of the Protege. Plus, they have a posting board where all of the Protege techies hide, including one that works for CorkSport Mazda Performance. If they dont have what you are looking for, rest assured one of the many Protege links they show will have it.
Definitely check out Paul Bonaccorsi's MP3 he is racing in the 2001 SpeedVision World Challenge Touring Car Championships. Paul Bonaccorsi has won three SCCA Showroom Stock C National Championships. Two of those championships were in a 1997 and 1999 Protege ES. You can check out his website here.
With the factory speakers, the imaging on the sound system is terrible. while positioned in the drivers seat, a person's leg blocks sound from the drivers front speaker... and you can forget about the rear ones.
When I replaced my speakers, I chose the Infinity Reference two-ways with the adjustable tweeters. The speakers are around $100.00 per pair and made all the difference in the world.
With the Tweeters properly positioned toward each person occupying the nearest seat, I found the sound stage to improve immensely without the need to buy and install component tweeters.
The only drawback I found with these speakers is the nead to drill into the door. The factory speaker holes don't line up the way normal speakers do. At first, I took the speakers back in order to find models with the proper mounting capabilities, but none sounded anywhere near as clean and full to me.
If you decide to reach for the mighty drill, be sure to use some quality sealant behind the screws, to prevent corrosion. As far as I know, the doors are galvanized.... but, there's no need to take chances.
Here's the link to Crutch fields web site.
Circuit City also carries this model.