Got the ITG intake installed and yeah, definitely needs a few adjustments for the USDM FiST. Fitment is way more of a hassle than it should be.
As expected, temps are considerably better than the ramair intake or the stock airbox. The peak temp I saw was 117° versus 141° just last week in similar conditions. At highway speeds the temps were +/- 1-2° ambient versus 15-30° above ambient for the ram air. For reference, the stock air box was only about 3-5% better than the ramair intake temps and that's likely attributed to the stock air scoop so yes, the ITG/Peron design is an improvement but hard to justify the price given fitment.
It's just as loud as the ramair intake, possibly a bit deeper and less overt at parking lot speeds, so a win there.