Why is a dry flow filter better then K & N?
Yep; as already stated cold air is denser than hot air, has a better flow, and creates less turbulence in the intake tube for a smoother air supply.
A filter replacement is better than the air intake kit because the factory airbox draws air from outside the engine compartment and delivers cooler air to the engine.
Dry flow is considered better because it uses no oil on the filter (K&N uses oil impregnated gauze). Oil from oil impregnated filters has been known to cause early failure of intake sensors.
The biggest problem with K&N filters is over oiling at service time, most people refuse to read and correctly interpet the instructions, so if I'm recommending filters to someone I suspect may not be mechanically savy I usually recommended a Dry Flow which uses no oil.
Remember tho K&N is a great filter when properly serviced. I use K&N on all my vehicles, and have for over 25 years.