After the plumbing of the water lines...i was wondering if this is going to make the engine run any hotter since it's taking some of the water? Is an upgraded radiator or something necessary to keep the engine cool? If so any specific type i should by? I was looking at the PE one since i'm getting that kit....but any other options suggested? Or is it not even necessary? thanks!

 

The additonal thermal load is pretty low compared to the engine as a whole. You don't need to upgrade the radiator just for the water cooled turbos.

Many Z's are driving with twin turbos and stock radiators. The only issue there have been with cooling so far are Autos with a high stall converter. Those create alot of heat and the auto fluid is cooled by the engine coolant.

If you upgrade the radiator or cooling system it should be due to other factors i.e. road racing, desert climate, land speed records or what ever, not just for the turbos.
Gary