I just put the Evolution 3000 in my 07 vert yesterday.
I bought the plug and play harness from
www.quickconnectproducts.com.
The unit works great after you play with the volume settings.
The most difficult part of the install, was where to stuff all the parts and the huge harness involved.
There is a small amp, the wireless transmitter, and enough wiring to reach cross country. After about a half hour, I found what appears to be a good solution. Had to drill 2 small holes to route the power wire and the mic. I mounted the mic on the dash, by the driver side "A" post.
Sorry no pics, daughter had the camera. If I get energetic, maybe I'll take it apart again and take pics.
Getting the climate controls and Nav unit back in, was kind of like sitting on a suitcase to get it closed.
It was worth the effort. Now I can get rid of Onstar when my contract is up.