mercedes clk 2.7cdi late 04

[johnny4]

been driving around and ive noticed a blowing sound when turbo kicks seems to be only on when turbo kicks in hold foot down noise seem to go and it might be me ( keep looking in back window know )but it seem alittle more smokey when driving when turbo kick in anyone now what cause the blowing noise and can it make car more smokey with problem

thanks for any help

johnny