A/V upgrade help

[vip808]

I'm in the process of adding a Eclipse AVX2404 , two Vizualogic monitors, and other goodies into my 2005 H2(just bought it a couple of weeks ago).
I was hoping to get some input on some installs because I was hoping to keep my OnStar and so far it isn't working. I believe my installer is using Soundgate products to do the install.
Right now I have the H/U and mointors in and hopefully by this Saturday my XBox will be molded into the center console and my center channel will be done.
I'm having problems with engine whine, so I bought Magnecor ignition wires but it didn't help.
I've been in touch with Soundgate and they have informed me that there are some bugs with the H2 interface that they are working on.
Has anyone successfully replaced their 2005 stock system and retained their OnStar features? If so what products did you use?