I can imagine getting the speakers amp etc from a car with the uprated sound system is next to impossible bit of you could, is it easy to retro fit it into a 03 car?
The 10 speaker DSP system, is IMO a great system. The amps alone sell for £250, so at that price it's a good buy, BUT I can imagine fitting the loom to be a nightmare requiring disassembly of virtually the whole car!