So I just bought an 04 6.0 and it seems to blow a lot of black smoke at a hard acceleration witch I would kinda expect but it also seem to have alot of turbo lag all iv done is cold air intake and cat back exhaust will some tuners do this I'm not sure if prev owner might of put one on it is there a way to tell or do you think there might be a problem seems to run great once turbo kicks in cause it takes off like a mother please help thanx.

 

You could take your turbo off and clean it that might help ya out. There are a few video's on YouTube about it. Also then you can give a good look over .