cooler air is going to be more dense and is going to allow for a bigger combustion, thus more power. on a somewhat related note, I got in a debate with an older family member that has been mechanically inclined for years (working on cars, trucks, bikes etc) on his truck, he was claiming that a larger diameter intake (after the throttle body) is what would increase HP, told me how companies use this design, and claimed it was allowing more air in (because of the size). I could understand if perhaps the shape of the pipe allowed for less turbulence when entering, but to my understanding of basic physics, the smallest diameter, ie the throttle body, would make anything before it useless. Air works the same way in many aspects as water does. If you take two buckets: one large, and one small, and have a drain pipe exiting below it with the same diameters, they are going to drain at the same speed, so same principal for the intake right? Any thoughts, and or confirmation? is it maybe friction that plays a key role?
