When I was at the track the other day, and last night people noticed some black smoke coming out of my exhaust. I didn't think too much of it while at the track, because apparently other LS-1's were doing the same ( I was at the pit or in line so I didn't notice). Is this normal or should I be worried?

 

black smoke means your running rich

usuall cars with headers run rich until they are tuned for the proper a/f ratio