If your replacing everything (headunit, amps, and wires), its time consuming but not that bad. These cars are well put together, so in turn, they will be hard to take apart. It's definitely worth it IF he's going to keep the car for a while. If he's not, wait til the next car, and start fresh. Bypassing all the factory stuff is really the way to go in these cars. If you think about it you have a car that is relatively unchanged since 1992 (on the 3-series), and probably further back than that on the audio portion of the car. So now you have speakers, headunit power, audio design, etc. that is dated back 15 years, plus the components themselves are 10+ years old. Swap em and enjoy the new found sound...
-There are 10 kinds of people. Those who understand binary, and those who do not.
-If we ever forget that we are One Nation Under God, then we will be a nation gone under...Ronald Reagan