IMHO: Difference in power gains wont be noticeable... I say that as a OPINION - dont want to start another internet battle... the theory behind the ram air producing more power and less fuel economy lies on the fact its supposed to shove more air into the cylinder -- more air means more fuel to keep the mixture ratio the same... more fuel/air = more power and of course more fuel also means less MPG...
Short ram air intake takes air from a short distance away from engine usually on top which means the air is hot... hot air is less dense.. less dense = less power which means on some intakes the gain in power due to more air is negated by the fact this extra air is less dense...
Cold Air intakes take air from an area away from engine (usually from bottom front of car) which is "cold air" - this cold air is denser than the hot air around the engine bay. Denser air also translates to more power. Nothing comes for free.. by taking air from "lower front" you do get colder air but you also run the risk of hydrolocking your engine(water ingestion into engine through air intake)
IMHO: Both try to do the same thing in slightly different ways... if I lived in wet places like Florida I would stick to short ram air intake and put a heat shield around it... here in California CAI's do just fine (water? what water...)
