Howdy,
We just bought our first Mustang (05 GT Premium) and it came with the
Shaker 1000 upgrade.  We have two issues being worked at the dealer and
if you've ran across these issues, please post a reply.

1.  The stereo will not stay at a constant volume.  We've turned off
the "speed volume" but this hasn't fixed the issue.

2.  Something is draining the battery.  If the car sits two days, the
battery is pretty much dead.

For those of you interested in the Shaker 1000 upgrade, let me pass on
a little information to help with your decision.  THIS INFORMATION WAS
TOLD TO US FROM THE FORD MECHANIC:  It takes 45 minutes to diagnose
each amp, there are six amps total, and the diagnostic test must run
consecutively, in a specific pattern.  Each issue with this stereo
requires the mechanic to re-start the diagnostic test, which means
about 6 hours in the shop for the car owner........  Yesterday the
diagnostic test wouldn't go past #3 amp, which required him to restart
the diagnostic test two times..

Ford has required our Ford dealership to send in the defective part(s),
and they will fix and return them.  It took three weeks to get the
first two amps repaired (actually Ford said they would repair them, but
ended up just sending back new amps).  I wonder if it's that hard to
keep extra parts on stock at Ford.

This is my first Ford Vehicle, but the rental they have us in right now
has a better sounding stereo than our $1,300 upgraded stereo (a stock
Chevy Malibu stock stereo).