I can't remember the exact intake temp. difference but we put a Safari Snorkel on a friend's FJ60 Land Cruiser and his intake temps dropped significantly. He was using the Edlebrock Pro Flow EFI and it lets you monitor intake temps from inside the cab. I'm not sure that this really is that big of HP gain. And others could argue that it gives a ram air effect on the highway. Really they keep water out and the other benefit is that the air they suck is usually cleaner at that height when compared to stock on a dusty road.
ya i tried both calmini doesnt have any and i looked at rocky-road and they said that they are temporaly out of production. i first looked about 4 months ago and it said the same thing then as it does now so i contacted them and are still waiting for a reply.