you could do what the EVO guys have, hook up some intercooler sprayers, that should help bring down temps a bit, especially at speed

Excuse my ignorance here but what does the turbine housing have to do with Intake air temperature, maybe the compressor housing sure i could see some effect there, but that wouldn't make much sense to me either because one would think that so long as the chosen turbo runs through it's best path through the adiabatic efficiency islands when mapped to the flow of the motor, considering that adiabatic efficiency is the percentage of wasted energy due to the act of compressing a gas compared to the ideal amount of energy it takes to compress that gas if you are traveling through the 73% island that means that 27% of the turbo's energy is being converted into friction and heat instead of pumping air so basically what i'm trying to say there is to my understanding it doesn't so much matter what the flow of the housing is so long is the turbo is correctly mapped for the application you will see the lowest possible resulting iat's from the turbo. The next question i would have regarding this is that i would agree with you in that the intercooler size does not particularly matter so long as it is more efficient than any intercooler known at shedding heat, being that we are stuck with aluminum i would say that a larger intercooler is always a better thing because even if your turbo(of course matched to the motor) was belting out charge temps near 500 degrees(i dunno like a pro turbo drag car) if your intercooler has enough surface area and an appropriate temperature delta from the cooling media (be it air in cosmo's case or a very large chest of salty-icewater in the case of our dragster)than it would be entirely possible to reduce the temps solely through intercooling down to almost ambient (or below in the case of a monster chilled turbo[or supercharged] dragster). Also 15% is a common number but there is always improvement, by my math (calculating the density of air with the pressure held constant) for every 10% increase in air temps around the 100degF mark the air will get 3% less dense so going from 15% to 5% could net you a 3% gain in power(or just prevent a 3% loss). And while checking before and after iat temps while cruising won't tell him if his intercooler will keep up at wot it is a perfectly accurate way to check to see if his modifications have had a positive or negligible effect on the efficiency of his intercooler at speed. I would think that he has done some good work and found some valuable information that will help members of the forum out, but again I'm not the expert here and i'm always wiling to learn.

I often wonder if our intakes were Plastic (since metal acts as a bad heat soak) how much that would effect the IAT's.? Referring to the entire tube from the throttle body passing through the engine area to the intercooler.. It is possible because most cars now have plastic intake runners just for the heat soak..

The problem I think might be plastic can expand and with forced induction you do not want that.
If you want to counter any heat soak you can do thermal coating, intake pipe wrapping, or even do the gold wrapping stuff.

Yea I didn't think about it expanding but do you really think it would at a low to medium boost? Considering the plastic would have a decent thickness too. I would think a heat wrap would hold the heat in considering isn't that what its made to do?

The expanding part wouldn't be that big of a deal..

Schedule 40 PVC (the white, cheap stuff) @ 3 inches is rated @ 158 PSI operating pressure...

So if you had some piping made that was maybe half that thickness, you'd theoretically be in the 78-80 PSI range for operating pressure. That's @ 73 degrees f.

PVC wouldn't be a good choice for this application, it can't really handle the temps for any length of time, but I just wanted to use it as an example of good thermoplastics' pressure handling characteristics.

At the very least, plastic cold pipes could be used, but the tooling to manufacture them would likely be prohibitively expensive. Same goes for a composite design.

You are focusing too much on the compressor side. Remember, everything that flows out of the compressor goes in to the cobustion chamber, fuel is added and ignited. The volume of exhaust gas going out and through the turbine will be much larger than that of the compressor. If the turbine is too small, you have high back pressures, and efficiency goes down the turbe. As a result IAT's sky rocket.

If I was to use a T3 .82 a/r housing for example on the VQ37 (compressor side stays the same), there is no way any of my customers would be able to get to 500whp due flow restrictions of the turbine, increased heat (IAT's) and back pressure. Instead I use the much larger T4 1.15 a/r housings, and IAT's are never an issue because the system flows so well.