Tach I would like to install in my new Astra twin top ne discreet but also loud system. I thought about the passage in the middle of the rear seat 23 cm diameter however where do I get the best current either for a small end stage or an active system, and probably the most important from where do I take off the high output from the cd30mp3, I install front and rear even new better speakers are front 165cm outer diameter and rear 120cm correct? and what kind of impedance d he originals? mhhh ask about questions I hope you can help me.. if even one might like such a sub-know who goes in there or an active cube that fits while I would have you very connected 23,5x27cm place Thanks Grassator