From what I've read, the Scion/Pioneer stereo is okay, but the speakers are thin. What speakers would you add when on a low budget?

 

I replaced mine with the Pioneer 2-ways from Walmart. 4" in the dash and 6.75" in the front doors. A friend gave me some Sony 3-ways, 5.25", that I put in the back.
If you are handy and not afraid to tackle it yourself, the factory front door and rear speakers can be CAREFULLY removed from the speaker housing and then reuse the frame/housing for the new speakers. The 4" fit in the dash without mods (just remove the two unused tabs) In all cases you should keep the factory speaker connector and reuse it on the new speakers. The easiest way is to carefully cut the wires at the cone of the origonal speaker and solder them to the connector posts on the new ones.
If you do a search on replacement speakers under this forum for the past 6 months there has ben LOTS of good stuff posted.

Walt