it may be because you're running boost in situations where you normally wouldn't (low throttle applications would usually divert more air into the intake bypassing the S/C), but now with VGS you're boosting with low enough pressure that the system can't cool the charged air. Mash the gas the temps should drop, right? I run the detroit tuned bypass valve for a more elegant solution to the issue. I have no way to check temps, but I wonder if that alters the equation? Or maybe I spent more $$$ to heat up my charged air . Then that part might qualify for this list )

 

If the BPV is shut when the engine is not under load, the SC is creating unnecessary pumping loss as heat...

 

No doubt.
With the BPV disconnected & tied shut, on this car, I don't see IATs anywhere near what you see. I know this is happening to more people with the VGS mod than the people posting on NAM. It's the why..... mp5999 with a 250, that's a big number..