So I am new to stereo systems and want to upgrade the stereo, speakers, and I have a box I want to put some stuff in, in my 91 JIMMY. So far its all stock and the stock speakers kind of suck. The headunit is the stock am/fm/cassette. And is about as tall as my cobalts radio was so I belive that means it is a double DIN. Can someone point me in the direction of a good cd/am/fm headunit that will work with mp3 players. Good speakers to swap the stock ones with I was thinking of 3 way speakers; again looking for input. I have a box that has 2 6" or 8" openings in it and 2 3" openings so I was thinking of getting 2 smaller subs:::dont care to rattle the car::: and what could I put in the 3" openings. I have no clue what was in it before some old lady gave it to me for free. Would I need an amp for a simple system like this or what. Some help guys because I know some of you have some badass ones..

also I have all of the wiring diagrams and plenty of quick connects and asst. wiring connectors.