99 Mazda Protege New system looking for suggestions.

[99DX]

the bass is taken care of in the car with 3 kick comp 10s and 1 mtx blue thunder 600w rms into 1
225 into 1. ran in a series

I need a head unit
a pair of 5x7s and 6x9s unless someone thinks those type of speakers need to be changed to 51/2 or 6 1/4s
I need a decently cheap/quality 4 channel amp
and a pair of tweets to run off the radio

thanks
B

[99DX]

900 dollar budget btw for install and equipment