Anyone interested in this make sure you don't have a DSP carver system. Would be good if OP could post what system he has so potential buyers know what cars it will work on for sure. Would be waste of time and money if someone buys it and then only realises afterwards it's incompatible without major costs and extensive work.
When I did mine I had to get a £600 amp, full re-wire, some of these crossover gizmos, etc. So make sure your system is compatible with just a straight head unit swap before hand.