Black smoke
 

So I just bought a 2004 Ford 4x4 with a 6.0 I am a truck driver so I am somewhat familiar with diesels just big ones but it seem to lag a bit at start but runs strong once turbo spins up and it seem to blow a lot of smoke if I step on it is this normal for this truck all that I know that has been done to it is a s&b cold air intake and a 4in cat back exhaust with a 14in magnaflow muffler with 5 in tip and the turbo seems kinda quite any advise or comments are appreciated thanx.