Since you are running an electric water pump, I double check the flow of water is going in the right direction, I would not hurt to test and or replace your thermostat either. I got a little confused with your description of the water feed connection point to your turbo. Not sure what other have done [im sure they may comment], but I would be tempted to tap into the water plumbing cct at the back of the cylinder head where it feeds the cabin heater.

cheers
benny