I made something custom for my Hatch a few years back.
It weighed a ton (well...30kg's to be exact

) But sounded pretty ok for me at the time.
Pioneer HU, Pioneer 3-way speakers, Infinity 10" sub and JBL 4-channel amp.
I added some custom lighting aswell later on.

For anyone who's wondering what BLØF stands for: Bløf is my favorite Dutch band
Was going to fabricate some custom door panels to be able to build in a 16cm compo-set in the front. Never got around to it.
Did make this for my current Carina E GTi though:
This setup does sound nice. With those Pioneer High-end 16cm seperate 2-way speakers, I don't really need a extra subwoofer.
Set-up in the Carina E:
Pioneer Head Unit
Separate 2-way High end Pioneer 16cm speakers front
Separate 2-way Alpine 12cm speakers rear to back up the front
All driven by a JBL 4-channel amp.
Still a budget set-up. Didn't want to spend to much money on it but I was pleasently suprised with the result!
And as some of you guys may have noticed already: Yes, I hate loosing space in my trunk for audio. That's the reason for the elaborate set-up in the Corolla and the reason why the amp sits where it does in the Carina