Recommended Aftermarket Stereo Mods

Anyone know of a site where I can learn about upgrading the base stereo in my Z?

There's room for a subwoofer behind the driver's seat (Courtesy Nissan has the Bose Cover for about $6), and seems like there's room for an amp and such.

I'd like to keep the stock dash unit and upgrade the power and speakers all around. Suggestions?

I just had my stock stereo upgraded by changing out the front and rear speakers with Infinity's, (component front and coaxal rear) and adding an Alpine 4 channel amp and putting an Infinity Basslink Sub in the hudge cavity behind the drivers seat and used the Bose Grill I got from Courtesy Nissan. It took the stereo shop all day to do it. Everything looks factory but not the sound. I think the installers would have done it for free and they sure didn't make any money since it took them all day to install everything but they did an excellent job.