You can use any head unit, the monsoon sys. amps don't use a remote turn on, they use signal sensing, so if you change out the head, the factory amp will turn when you turn the head on and the cool thing is that they automatically adj. themselves for the amount of input voltage,
The only problem with this car is that it may have the gm class II databus system through the factory head, so if you change it out you will have to relocate the factory head and wire it up, Best Kits makes a bypass harness for this, BHA2004t (I think that's the number) and would cost about $70-$80.
The above information is being provided free of charge on an "as is" basis, without representation of warranty, it is your responsibility to verify any of the above information. I assume no liability and accept no responsibility whith regards to accuracy or currency of the above information. Proper installation in every case is and remain the responsibility of the installer, and I assume no liability or responsibility resulting from an improper installation, even in reliance upon the above information.