I doubt that on a 2.8jtd that will achieve anything other than to make the noise worse, as the turbo is maximum pressure cntrolled via a small pressure hose to the wastgate control capsule. It is not controlled by a variable vacuum as on more modern engines. This small pressure sensinng hose is I think the one referred to by
@Adie1023 in post #6. The hose is not otherwise mentioned, and I have not read of any failures, but it is subject to the same pressure as the rest of the system. Although the front subframe impedes access perhaps worth investigating, as it could be leaking.
Do bear in mind that the turbine or exhaust side of a turbo can get very hot.
I am attaching one of my stock photos, as it shows the hose below the gear selector cables. The photo also shows location of speed and crank sensors, so should be informative to an interested newbie.
Has anyone got any suggestions as to how to inspect the hose?