Okay so I'm already not very happy with the whole sound setup that came in it....
sony xplod cdl550 or something cd player...
he said rockford fosgates in the front, ill assume 4", and sony xplods in the rear...and i got the rear panel loose enough to confirm they are an xplod but i couldnt tell how big...imma guess 5.25"

anyway first question, how do I get those rear panels off when I decide to replace them? It looks like its one huge piece and I couldn't find screws...so I'm guessing I wasn't looking hard enough but I was in a rush to get the thing washed before the sun went down and then didn't have time again to mess with it and figured i should ask before i tore something up.

and should i replace the headunit first to see if my crappy sound is from it, or should i go ahead and replace it and all speakers? it doesn't get any bass out of them (obviously the 4" won't get any, but i figured the rears should have some?) and it sounds really bad all around at low and high volumes...and there isn't a good median either. im guessing just the sony stuff is what i need to replace cause its crap :-D?

and would 5.25" midbass be a good size and type of speakers to put in the rear? found a guy on a local car forum thats selling two different sets, i believe jvc and kenwood but not sure what he wants for em.

 

Sony Xplode head units are not crap, as I own one and it rocks.
My system pumps.

Your lack of bass is due to two things:
1. Small speakers
2. No external amplification.

Check out my audio page in my sig below if you want more bass and volume.
I'd steer clear of putting the speakers way in the back there, as you need mid bass and highs up by you, and you really only need two good speakers up front in your front doors.

My doors were modified of course with custom pods, but you don't even need to go with that, a riser block circle, enlarge the whole in the door, and a pair of good component speakers will fit up front.

Put a sub woofer in the rear, and you will see a dramatic change in sound.
You could even run one 4 channel amp to handle all of this.

I am not familiar with the model head unit you have, but one thing to look for in a head unit is to make sure it has RCA out jacks(pre-amp out), and 3 of them.
Two for the front channel speakers, and one for the sub woofer.

Hope this helps.
With my setup of just 3 speakers, it rocks and plays at high volumes with no distortion, just good clear tunes.

If you do build your own system, there are numerous posts on the forum about speaker choices, amps, ect, and what size wiring to run.