black smoke out exhaust when getting on the highway
 

just curious what would cause a thick black smoke comming out of the exhaust when jumping on the highway I floored it and it just poured out. truck was feeling for 5min before so It was a little warm. I only have a superchips tune on high performance mode which only does a little smoke. tranny was rebuilt and also replaced a turbo boot clamp. I'm just curious if I should be checking something out