I just explained earlier that you'll lose HP with the bypass valve, thus telling you to get a short ram intake because you'll get the same performance (meaning lower hp numbers than the CAI). Look at it this way, the short ram is called a SHORT ram because it's short. The shorter piping will absorb the hot engine air compared to its longer CAi counterpart because the CAI's piping is longer and the cone filter is positioned lower and away from the engine.

Cliff Note: Heat = bad, Cold = Good

For sound, the cold air intake is louder.