The Rover-Landers of BC

I’m new to Diesel engines, and am looking for a bit of advice.
I picked up a 97 Disco that has had a 300tdi and 5spd swapped into it. Love it. The previous owner swapped out a bunch of the piping to terra firma silicone replacements, but told me he hadn’t done the “ little one in the back” it has now developed a whistle under load or acceleration, which I can’t replicate stationary. He seems to think it’s the aforementioned “little one”. Does anyone have an idea which one he’s talking about and where I need to look for it?? :?:

Normally a whistling noise under load is a boost leak between the turbo and the engine. Check all of the connection and hoses carefully.

He could mean the boost enrichment line. It goes from the fuel injection pump, usually around the back of the valve cover to a boost pipe near the turbo. If this one is split or come off, the engine is fairly gutless however.

I know the 90 degree hose that exits from the turbo is small and black. I have had that one collapse internally which caused a breakdown on the Malahat.

I took me quite a while to track this problem down in my 200tdi. In the end I had to rig up a way of pressurizing the intake system with an air compressor to find a few very small leaks with hose connections etc... but the main issue turned out to be an exhaust manifold leak that only showed up under load, it was in a really difficult spot to see as well.

I think I found it, a small loose connection under one of the main hoses, snugged it up and seems to have stopped.