Toyota System 10 suggestions

Hi all,

 My car is a 1991 Toyota Celica Alltrac with a factory 10 Speaker stereo system.  My head unit has been replaced by a Pioneer 1300 CD player and when this was done, the previous owner removed the 220 Watt factory amplifier.  So now all 10 are running of the Head Unit.  As i'm sure you are already aware, this does not provide much sound in some of the speakers (even though i do have crossovers installed). 

  Basically i am wanting to slowly replace the speakers and add amps and a new crossover.  I am new to car audio so I could use some suggestions.  I dont have a ton of money, but i will try to get a good bang for the buck.  I'm not wanting thumping bass, just a full range of sound.  The spekers in the car are as follows:

The 8" in the doors has to be thin mount b/c i want my windows to work.  I was thinking Kicker RMB8.  What kind of crossover and amp(s) would you suggest to power all this?  I dont want my doors to rattle and i dont think there is any way to seal the doors - so it will be open air.  Also, i am not sure about wanting to add a Sub in the back hatch b/c i want to keep weight down since my car is fast and weight slows me down.  I appreciate the help.

The door is a mid-bass speaker.  This may provide enough bass for me..wont know till it's installed.  I realized that i can't put a sub in the door, that is why i will use an 8" mid-bass speaker like the Kicker RMB8.  I can buy a new component set for the front speakers with crossovers included, but what kind of amps should i get. 

Some people have done a 50X4 and powered teh front speakers and the door speakers with that amp, and then left the back component set to be powered only by the Head Unit.  I was thinking either a 6 way amp or 2 amps (one 2X100 for the doors and one 4X50 for the rest of the speakers).  What do you think?  Would i still need crossovers?