Ausome they are very handy.
Anything about removing the dash panel area to get into the head unit?
On my 04 WRX, it was easy enough..
Extend cupholder and remove two exposed screws.
I pulled cupholder clear from it's slot (ease up
the small tab on underside) but I don't recall if
that was absolutely necessary.
Trim ring around radio/HVAC stuff is held with
series of compression clips. Gently lift it up
starting at area below cupholder and work your
way around. Knobs on HVAC and air intake don't
need to be removed.
The OEM WRX radio/CD/tape unit is held with six
screws, all visible looking in past front panel.
While you're in there, you can detach the HVAC
control and remove the small brass screw holding
a microswitch on the right side, and defeat the
"A/C with defrost" feature (can always push the
A/C button if you want it with defrost).
Steve