Not sure about the 07, but I know the 03 had 4 possible stereos.

3 separate non-nav units; the first with no XM and a lower power rating than the next two, one of which had XM. The last is the navi headunit.

Sorry I don't recall the specs; but check to see if yours is just the horrendous sounding one. Maybe an upgrade is in order to a new factory unit.

If not, you can get something like this: http://www.bizrate.com/caraccessorie...areprices.html