it cant happen with a cold air intake, the air will always be cooler outside the car then the engine bay, the tempreture difference will more then make up for the increase in drag from plumbing
a short ram intake is useless, the less piping you have the closer the intake will be to the engine and/or radiator which will heat up the air giving you lower oxygen content, a REAL ram intake will have the intake exposed to the outside effectively "ramming" the air into the engine, this usually means cold air as well but aftermarket parts NEVER do this
basically same as what i said before, check out what you're buying before you buy it, but since that's out of the question just pay attention to where the intake is located, if it's near the radiator or engine it wont be that good but if its low enough to the ground (at most 1 inch higher then your ride height) it should be ok, the best of course is in front of the radiator since it wont disrupt airflow over the car (like a bonnet scoop) and will still give a slight supercharging "ram" effect"