cd player install: 2004 GTP GP with monsoon

[jesspren6]

I have a 2004 grand prix gtp with amped monsoon system + onstar. I found a wiring harness so I can hook up my pionerr cd player but it has bad rating from the reviews. I was wondering what I should do, but I have some questions.
How many watts is the monsoon amp?
What wiring harness works good that I can retain my onstar, warning chimes, etc?
I also heard it will cause a popping noise when i turn off or on the car because of a 12v drop, what can I do to fix this?
What can I use for steering wheel control adapter?
I would like harnesses that I can straight plug in for the steering controls and the cd player, but I want it to sound good with no pop or distortion, and retain onstar. More info on my car: 2004 Pontiac Grand Prix - Suggested Retail Value - Official Kelley Blue Book Site

Should I get the GM Factory Integration Adapter(General Motors Class II data bus interface
Retains ONSTAR system, factory door chime, and Bose system with aftermarket radio)? Does anyone have experience of how good it works, by the looks of crutchfield it is a waste of 100 bucks but maybe they are car audio idiots lol

[flooger]

I think I have the adapter your talking about. GMOS04 or something like that. I got it to install my Alpine head unit in my 01' Grand Am last year and it didn't work with my Monsoon. I now have a 2004 GP GT and Crutchfield says that it's supposed to use the same adapter but I'm pretty sure it's sending too much power to the factory amp. I need to find the amp (looked in the trunk between rear speakers) and turn down the inputs and I think it would work. So basically in a nut shell I couldn't get it to work with my Monsoon but it seems to almost work with my factory amp in my 04 GP. I think your best bet would be to get a head unit with OnStar inputs and replace the amp. You would lose your door chimes though. Monsoon all together just kinda sucks. :/

[jesspren6]

Is there any way I can leave the factory amp in there, it's a lot of work taking out/ bypassing the amp.