I've got a td5 that's been modded and after a high speed run it's making a strange noise
hard to describe when boosting then letting off it's a high pitched whistle
I've checked the following : all hoses and pipes on pressure side ok exhaust manifold gasket ok no visable leaks
still showing boost on gauge
previous mods intercooler, silicone hoses , chip, mid pipe romoved, boost increased,over boost box, itg filter, egr valve removed
HELP ITS DOING MY NUT IN
thanks in advance