Well I do know this. If your stereo does not have the CD button then there is no connection on the back of the unit to hook in a CD changer.

If it does, you probably need to get a LEXUS model changer and the cable that goes with it and hope for the best.

 

It does have the cd button.
Thanks

 

You CAN replace just the speakers and get better sound (because the Pioneer and Nakamichi speakers are still basically crap), but to do this you need to get rid of the speaker enclosures too, and make new baffles. You can put in a new sub amp off of the Pioneer facory amp, easy. However, replacing the Pioneer stock amp and keeping the stock headunit is non-trivial, if you have the CD changer.