Re: Upgrade standard ICE
decent head unit can be had at any outlet, so long as you know what to look for. i personally recommend pretty much any unit made by JVC or alpine, they both make exceptional units with great clarity.
after the headunit, upgrades really depend on what you want from the system, if you just want clarity with minimal cost i would say get some good speakers to match the unit.
if your after mind numbing bass then you will be needing a large amplifier (means new wiring) and a decent sub. personally i think the best sound can be had from a half decent head unit, a good 4 channel digital amplifier and some good component speakers. as i say tho, unless your really into your music (im a musician) then a good head unti and some replacement speakers will more than do the job.
my 147 has the bose system installed and i cant fault it. its nothing special but for the job it needs to do its spot on.
oh, electrics, unless your wiring in amps and such (boot install jobbys) then the stock wiring is fine.