I have a 2001 Pontiac Bonneville SSEI with a the stock 8 speaker Bose audio system and the factory amplifier. I want to put an aftermarket stereo in (Pioneer). I want to also retain the chime and all the sounds that come with it. I do NOT need to retain On-Star as I do not have a subscription to it. I need to know what Interface to purchase to retain the sounds (warning chimes) and have it be compatible with a factory amp. I have looked into a PAC C2R-GM32R Interface but have been told that it does not work with a factory amp. Is it possible for what I am trying to accomplish. I've talked to many different car audio people and I keep getting different answers from everyone. WHAT DO I DO???? NEED HELP!!!!

Any certain reason you want to stick with the factory AMP?
You could get a decently priced aftermarket AMP that would work much better.

If you are sure you want to stick with the factory AMP, then you need this.
Metra Axxess GMOS 09 GM Amplified OnStar Class II Data Bus Adapter | eBay

NOTE: I read on Crutchfield that "Note: Your aftermarket radio must have two pairs of preamp outputs in order to properly interface with the GMOS-09. If it doesn't you will need to connect the receiver to a line output converter (such as item # 142SLC4, sold separately). The GMOS-09 will accept a preamp signal of up to 4 Volts. "

So be sure the deck you buy has two pairs or pre-amp outputs.
If it doesn't you will need this.
Scosche SLC4 Four-channel line output converter at Crutchfield.com



If you just wanted to retain R.A.P. then you'd need only this, it won't work with the factory AMP though.
Metra Axxess GMRC 04 GMRC04 Dock N Lock Wire Harness Chime Interface | eBay

I have heard from a couple different sources that you should stay away from Axxess GMOS-09 because it just stops working after a while for no reason. I bought the GMOS-09 once and put it into my car with the aftermarket stereo and my battery would always get drained. Was told that the software in the interface was outdated.

What kind of aftermarket amp do you suggest and where does the aftermarket amp go in the car?

most people do all or nothing, the amp on it separates the rear frequencies to the different subs and tweeters. aftermarket amps dont do this. but they are weak, about the same as a aftermarket hu. you can wire the radio to the factory amp and it will work that way.(the signals are mixed there the same as the factory one) if you want better, fuller and louder you replace the speakers and put an amp in that is spec'ed to power those.

So even if the interface says it'* not compatible with factory amplified system, you can still use it?

you can wire the rap wire to the amp. for the 04 one you have to hook it to rap circuit on the car. according to the diagram its a pink wire pin a1 at the amp. cut it, tape up the car side, solder an extention wire to it and hook that to the rap wire you run to the adapter. then it will be on when the rap circuit is active.

I'd really only go with an aftermarket AMP if you plan on eventually replacing the speakers as well, you could go with the speakers you have for now, but you'd have to reduce the AMP gain quite a bit to keep from blowing your factory speakers.
If you plan to replace the speakers and all, I can go over some decks, amps, and speakers, and find you decent sound for the money, just need to know a budget.

you cant really just replace the amp anyway the rear subs, door speakers and tweeters are separate wires from the amp. the amp breaks those up to different frequencies, it would sound funky if you tried to run one set off each amp channel and if you hook the speakers wires together it would be to low an impedance and it will damage the amp.