I have a noise that sounds like exhaust manifold leak, or air going through a line of water or a light slushy grinding noise. It all comes from the engine/transmission area and i can hear it loudly inside the cabin. I don't suspect a driveline problem because the noise gets louder when the butterfly plate opens more, not with speed or RPM. For example...in OD gear, attempting to accelerate without downshifting will cause this noise to get louder... I also don't suspect exhaust because I replaced the headers while doing my head gasket. I have no idea what it.could be, do you?

 

Did you find the answer to this problem? I'm have the same issue. It usually happens when hot