Audio Systems: 2005 Impala radio, subwoofer amplifier, peripheral electronics

Question
i recently sold my chev beretta 89 and kept the sony head, kenwood mono sub amp, subs and speakers. obviously i could put these in the impala - but could i keep the stock head? how would you suggest i wire my amp to drive the sub? if you recommend replacing the head would i be able to later reinstall the original - do i need a theft code to reactivate it or is it a simple swap? and lastly i do need the wire colour specs for this model year car.

many thanks. dave

Answer
I'm glad you have not started yet, this could have been ugly.
Your stock Impala head unit is databus connected to the vehicle's ECM. Some use the radio display for things such as oil change reminders and trouble codes to be displayed to the driver, all use the radio to produce warning buzzer and reminders through the driver's speaker. It is also theft protected by coding to the VIN of the car, and has to be reset by the GM dealership if it does not match.
Here is the cheap and dirty way to add your subwoofer, tie onto the rear speakers (they stay hooked up) on both sides and connect to the high level inputs on your subwoofer amplifier. If you do not have high level (speaker) inputs you will need an adaptor. Some aftermarket companies also make high quality interfaces that plug right into the OEM harness, supplying you with RCA level outputs. These do a better job, with less noise, pops, and thumps. Look at the websites for PIE, Scosche, Peripheral Electronics, and Blitz Safe. They also offer headunit replacement kits, but be prepared to spend some $$$.