A cold air feed is good...cold air is always good.
But, Ram Air only works on a sealed induction system...so if you go to the trouble of finding the highest pressure area at the front and duct aid from there, you will only see the (small) gain at high speed with a sealed induction system...and holes in the airbox and you lose the pressure.
You can add as much cold air as you want...but any holes in the airbox wing side, bottom or otherwise and you WILL be sucking in warm air as the engine will suck from the point of least resistance.
So a totally sealed airbox is best - except if you hit lots of standing water you run the risk of hydrolocking the engine.
Just ask the owner of my first GTI who hade to replace the engine after a period of flooding!
It's all a balance :-)