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Quick version:

Does it work - Yes
Does it matter that it works - maybe not

Long Version:

For the testing, we compared a stock sti to my sti with a APS turbo Back exhaust, trimed stock turbo heat sheild, gold reflective sheilding on the inside of the turbo heat shield, end tanks, and y pipe, and exhaust heat wrap on the hot side of the turbo(as best i could), the elbow, and downpipe.

One temp probe was hung in place from the brake lines on the passenger strut tower hanging in place. The second was taped along the top edge of the cold side end tank were it meats the cooling section but out of the flow of cool air so as to messure how how the outside of the intercooler was getting.

We first let the full warmed up cars idle for about 8 minutes untill the temperature fairly stablized and took a measurement. Then we did two cruising runs back to back accross the gandy bridge at constant speed.

Here is the readings

Stock STi

Idle: Engine bay - 158, Intercooler - 170
Cruising 1: Engine bay - 117, Intercooler - 94(probe was slightly in the air flow on first run)
Cruising 2: Engine bay - 123, Intercooler - 98


Idle: Engine bay - 148, Intercooler - 154
Cruising 1: Engine bay - 131, Intercooler - 98
Cruising 2: Engine bay - 134, Intercooler - 97


The stock exhaust with stock heatshielding is far more efficient than a totally aftermarket system with hacked heat shield making a more fair comparison a STI with a turbo back exhaust and no extra heat shielding measures. That said, from the idle numbers, you can see all thee measures seem to work quite well to keep temps down despite the extra head sheilding the stock downpipe has.

This however seems to matter very little once the cars get up to speed. Temperatures dropped rapidly as we accelerated past 30-40 with both cars seeing almost exactly the same intercooler numbers. This shows that the intercooler scoop and natural flow of outside air into the engine bay play a bigger role then expected.

For lower speeds, and off the line performance, these treatments could show an improvement. Or at least decrease the negative effects of heating at low and now speed situations.

This test and testing method is admitedly not perfect and lacks some important figures (hp and air temps entering the engine), but still shows some interesting results.
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