haha, I wouldn't consider having to use 4ohm speakers a bad thing... this means that you have the 2200 deck like me (a very good thing for people who want to incrementally upgrade their system! This means that you can go to whatever you car audio place is and pick just about any speakers and put them into your Legend and run them off the stock deck since 99% of the speakers out there are 4ohms.
Disregard luvmylegend's post above . You could put in an aftermarket deck in with your system as is right now. In fact the system that you have is the same one that I had, and is compatible with anything aftermarket.