noisy turbo....

[benchph1]

i just changed my batteries yesterday on our kia carnival.
when i drove it yesterday i notice a loud "hissing" sound when it reaches 2000 rpm and above. the ecu could have reset itself when i changed batterries, i tried to look where the hissing sound was coming from while someone revved the engine. as far as i know the turbo is mechanical so it has nothing to do with the ECU. whatcha think is the problem?

p.s: i know turbo's make a hissing sound when they spool up, but the sound it is making today makes it look like there's a garrett t66 turbo under the hood! yes its that loud!