Originally posted by G32BTurbo-
"but why? the "cold" air would pressurize in the turbo and become hot again"-

The turbo will only heat the air up so many degrees. If it is colder to begin with, it will be heated up that much less.

Kind of like the opposite of the air conditioner in your car. It can only make air coming in from the outside of your car so many degrees colder. On a day when it is 100 air temp. your air conditoner will only be able to make the air say 70 degrees, but on an 80 degree day, it can freeze your butt off.