Could it be leaning out thus making more heat ?
What have you done to give the engine more fuel under boost ?

Thanks for that feedback rob.

Pretty much the only tuning method available to diesels is the fuel pump.
I have been reluctant to wind in more fuel as I know that more fuel will increase egt's and I already have high water temps.
You are also right that tuning diesels needs finesse as too much fuel can quickly melt pistons and generally break stuff.
My egt's sit well below 300deg during normal use and spike to about 450deg during hill climbs and regular work loads and can hit 500deg. after prolonged heavy right foot work. They then drop off quickly once the load is off. This is all expected.

I havent used the most common turbo option and most of the chevy diesel nuts didn't have much to say about the expected result.

The issue is high water temps.
I have heard that too much back pressure before the turbo can significantly increase /affect temps both egt's and eventually water temps as the heat has to soak somewhere.

If I have a turbo that is too small would that increase back pressure resulting in more heat from the exhaust being soaked by the water rather than escaping out the pipes

A good and knowledge friend suggested that since I have added a bonnet scoop to feed the top mount intercooler that that will have upset the airflow and be causing heat to stick around in the engine bay rather than be flushed down and under the car.

My next option is to upgrade the radiator to a bigger unit. What bugs me is before the turbo upgrade overheating was not a problem so im reluctant to throw another $500 at the Pootrol when the dat deserves it.