Oh I didnt see your post inbetween mine let me go back and read that.
So, here's what I was going to suggest:
Keep the stock head unit. It isn't that bad, as long as you process the signal coming from it before sending it to an amp.
Use either a signal processor like my RF 3sixty.2, or the Alpine 650, or similar. OR, you can cheapen up a bit and run something like the MTX Re-Q 2, to straighten out the signal.
I didn't want to run amps but ok I'm listening, cheaper sig processor would be better then also
INSTALL SOUND DEADENING. DO NOT SKIP THIS STEP. SPEND A LITTLE TIME, AND A LITTLE WEIGHT ON THE DEADENING. If you are willing to put a little weight in the doors, go with Raammat and you can save a bundle. Use Ensolite over the mat, and you'll stay light enough.
huh and what?!?! never heard of either of these. I am assuming its like dynamat and what else?
Purchase quality 6.5" components. Most are pretty light and good.
I was thinking infinaty referance or polks db due to the reasonable cost.
a. do you like more crisp sound, or more smooth sound?
b. do you prefer it to be more loud, or more clear (or both at the increase in cost?)
c. what do you listen to?
punk rock
d. if you were at a concert, are you at the front row, or more in the back?
the back near the sound guy so it sounds the best
e. do you prefer things in your face, or more reserved and laid back?
This will all help greatly.
Purchase one single quality 10" subwoofer. I'm going to suggest the new slim subs now available from JL audio for this one. A single 10 in a properly designed fiberglass box will weigh very little, and importantly the weight would be low in the car.
can i use better speakers to save the cost of a sub amp and woofer?
I can explain this further if it is in your interest.