The time involved would have been 16 weeks or so (5days/week)...still isn't completed. I didn't do all the stuff but I did do some of it, mainly the computer part as the guy that did the stereo install didn't know much about it. Ran into lots of problems back then. I'm still tweakin it.
It's fairly loud. I have Replay Gain with MJ8 going so it sounds great on all tracks. I'll sometimes use the dsp..really makes a difference, especially the subwoofer setting.
I blew out the subs I had in the car a few months ago (too much power). I'll eventually put 3 12"s in there. They're about $400 a piece so it will be a long time yet.
Also, if I have the volume set to max, you can scream your loudest and the person in the passenger seat won't be able to hear you at all.
..and yes, I have passed my hearing test I took last February.