Yes, you can add some things, but it's far easier on a 2001-2003 Prius
than the newer 2004-? Prius.

You can go to your favorite Toyota parts source and get the 6CD changer
(plus fitting kit) to fit into the slot in the dash under the radio.
That'll give you a total of 7 CDs in-dash. I can get the part numbers
if you need it.

Satelite radio for the 2004-? Prius:

XM:
http://www.coastaletech.com/xm_radio_in_prius.htm

http://www.priusxm.com/

your favorite Toyota parts department: ask for the Solara XM radio
kit,
part number PT546-06040

one known Prius-friendly Toyota dealer has posted the installation
instructions for the Toyota XM kit, and is offering it for sale here:
http://www.metrotpn.com/ProductDetai...uctID=96&S or
tIndex=10

Sirius:

According to the thread at:
http://www.priusonline.com/viewtopic.php?t=4964

The Toyota Sirius kit for the Solara also works with the Prius. Part
numbers: PTS31-00051 (cable), and PTS31-00050 (Receiver)

http://www.metrotpn.com/ProductDetai...?ProductID=153

I've also seen:
http://www.siriusprius.com/
http://www.priussirius.com/

adding in a aftermarket Navigation system could be done with:
http://www.coastaletech.com/viewtech_2005.htm

someday CoastalETech may release their iPod/aux-in hookup:
http://www.coastaletech.com/ipod_interface.htm


On a Classic 2001-2003 Prius, a few people have managed to add a
"factory" navigation system to one that wasn't equipped as such from
the factory. They get their parts from junkyards/scrapyards, as new
that's over $4000 of missing parts, and then it's a few weeks to
install everything. (Missing is the GPS ECU (with the map DVD player
and the gyroscopes), a wiring harness, the GPS map DVD, the GPS antenna
(which lives behind *EVERYTHING* in the dash), several mounting
brackets, etc.) Really annoying on a classic, as it has map buttons on
the dash that just say "external system not connected" if there's no
navigation hooked up. Some unknowing used buyers can be easily duped
into thinking they have navigation...

No one has been daring enough to do the same to a 2004-? Prius. Then
again, besides the above, they'd also have to swap out the steering
wheel (more buttons) and the display (which comes with the side bezel
switches), and maybe also the center map light area (microphone for
voice commands and bluetooth phone).

Basically, with used Prius pricing still very close (and in some areas
of the country, better than MSRP), if you really miss the navigation
system and you want to get the built-in cassette player of the upgraded
JBL 6CD unit, then you might consider ordering a new Prius with the
stuff you want, and selling off your more basic 2004.

You can find all this on priuschat.com

If you didn't buy the NAV with the car, a separate Garmin or other unit
would work but it is not as elegant, but then you can take it from car
to car.

XM can be installed by the owner. I did mine. Not too hard. If you want
to buy the official DVD for the how to install from priusxm, I'll let
mine go for $15 + postage.

Bill in Cary, NC