Out of curiosity does the cold under like 30 degree's affect boost?
I hear that it's ideal around 50-60 degree's and turbos run like crap if it's too hot.

 

i noticed with mine i had to turn my boost way down as soon as we got some sub 30 weather

 

My boost fluctuated 8-10 PSI (no I'm not kidding) from 60 to 25 or so, I have a larger set-up though which I know has something to do with it.

 

that sounds about right mine was about 8 psi difference

 

*update*

I had asked a close friend of mine who drives an STi he gave me a long explanation but in a nutshell what he had told me:

The air is thinner in the summer / Thicker in the winter
The car automatically compensates the amount of air the turbo takes in to produce the same output.

So where it's been cold the air has more density.

 

If its computer controlled the cold air will produce less boost to make the same amount of power just a little bit over. With warmer air the car will try to produce slightly more boost to compensate to make the same amount of hp.