hissing sound from turbo?

[RILOW]

ok guys got truck all back together and truck runs fine, but have a hissing sound fron turbo area , when idling it comes and goes and when it is hissing is i unplug the sensor plug on top of turbo (vgt) it stops, connections to y pipes are good cause had to redo that one dont feel any leaks from drop pipe either. any suggestions as to where it can be coming from. trucks 03 f550 just put oiler cooler and egr cooler, thanks for any suggestions

[RILOW]

found where it is coming from, the connection between egr cooler and exhaust pipe. never got the connection just right, took turbo back off and got it line up just right now. hopefully finish it back up tomorrow. when making the turbo connections have to take time and make sure their mated up just right. my fat ##z aint made for workin on these, man my stomach is sore. hope im just about done for a little while