I'm not going to mess with thermostats unless Prodigy tunes for it. Modern engines are designed to run at higher temps for efficiency and emissions, and I don't want to risk throwing things out of balance.

Yes, the pentastar does have coolant passages in the built-in header. If exhaust temps are not causing excess under-hood heat, then any attempt to reduce exhaust temps would actually hurt performance. Turbos are driven by the heat expansion of exhaust leaving the engine, and the pressure differential across the turbine.

Speaking of which... minimizing post-turbo exhaust pressure is probably a good thing to look at. Zero exhaust pressure post-turbo would be ideal. A first step would be to actually measure exhaust pressure in the stock exhaust system with a turbo to see if it is a major restriction to begin with. Reducing pressure hear would also improve volumetric efficiency, and reduce post-turbo exhaust temps, which would all work toward reducing under hood temps a bit.