Yeah! I was at Chris's place this past Friday to have a DeWitts radiator installed along with a few other underhood goodies. While I was there Chris put the C5Z on the dyno and noted that under boost it is running WAY too rich. I too noticed the black smoke coming out of the exhaust, which I had noticed before. Was supposed to go out there this upcoming Thursday, but I've got to be on a jury that day, so that screwed that plan.
The place looks real nice and Chris was very gracious showing Connie and I around the place. They are only about an hour away from us, so it's not an overnight affair to get the car there for work.
All in all, highly recommended....