Thanks for the info guys. I have new updates on my audio system. I just got a Pioneer DEH-6800MP. It has 3 pre-amp outs, so I'll also set up extra front and rear speakers in the doors. About the trunk as baffle, I think I missed some details. I removed the first aid compartment, so this gives me a free path to the trunk. Then I made a flat spacer with 1/2" medium density board that covers the whole space where the compartment was. I made a round hole and putted my subwoofer facing downwards (coils inside the cabin). I haven't pluged it yet. I'll post some pics when I'm done.

What do you think of this guys?