I bought my car about 3 weeks ago and needless to say the system that was in there sucked! So I decided to do a little upgrade and what a difference a few bucks (approx $400) has made..

What I added:
Infinity reference 6 X 9 3 way

Infinity reference 4 X 6 plate speakers (4 inch round plus a tweeter).

Kenwood 8104 Amp (300 watts at 4 ohms)

1 JBL 10" sub

Built the box using 3/4 inch MDF and sealed with liquid nails

The car already had an aftermarket Pioneer head unit which I decided to use for the time being.

Ive only got the gains turned about halfway up and this system sounds awesome!
Here are a few pics of the sub and amp

 

The sub box looks good sunk way down in there... do you know about what cubic footage it is?

 

Honestly I dont know what the cubic feet is (its a full box--not a plate). It took me a couple cuts to get it right (its a tight fit). I have got more bass than I know what to do with (seriously)!!