You're explanation is exactly right. There are a couple explanations. The simplest is that they were tested under slightly different conditions, but also that with the increased pressure drop in the OEM unit, the turbo has to work harder to make the same amount of 'delivered boost'. Compressing the air is what increases it's temperature, so the harder the turbo works to make boost, the hotter the compressor exit temps are. The 'Pre-IC' temps shown above are collected just before the TMIC; they are not IATs, taken at the MAF.
The temps plotted are also before any heat soak, so the OEM TMIC keeps up with the stock turbo pretty well. We've got a lot of these in tester hands, so there will be a wealth of data available shortly, but when the OEM TMIC heatsoaks, it becomes darn near useless. The GS stays very consistent.
If you're a numbers guy, keep an eye out for more reviews and testers. We've got guys knocking on 600whp already!
Matt Beenen
Engineering
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