So am I mate, I'm 27!
If you want decent bass, you really don't want MP3's. It is the first frequency to get cut off and the difference is massive. I can see the attraction of mass storage, but there is a quality trade off.
I have a JL Audio 10W7 - I have yet to have anyone in the car that thinks there is less than 2 x12"s in the car, but the quality is also there (one or two others on here have heard it).
But it has to be driven by the right signal. If the frequency isn't there, the pre-out can't send it, the amplifier can't amplify it, the speaker cable can't carry it, the speaker won't produce it and you won't hear it. If anything in that chain isn't doing it's job, it won't work. I am running a JL Audio 500/1 that puts out 500w RMS - regardless. If you are talking the usual JBL / Kenwood amp power output claims it is about 2kw.
One of those Alpine screens will allow mass storage connectivity, Bluetooth for the phone, full iPod control, DVD / CD changer control and Bluetooth audio too.
I would say something like a decent screen / controller like the Alpine, a set of 6.5" components (JL, Rainbow, DLS, Focal, Hertz etc.), a Genesis / JL / Audison monoblock amp for a sub and one for the front end, and a JL sub (not many others cut it IMO - maybe the Focal) then you will have a fine high end system. But you'd be looking at about £3k for kit alone.