If you put it on the dyno and tested before after, yeah, you'd make no hp or lose HP because your car needs a day or two to re-calibrate, and your 2nd run is always less than your first. Furthermore, an intake doesn't add 30hp. It adds just a few, which can be counteracted (and then some) by temperatures, etc.
These intakes do not lose power. Nothing could be less free-flowing than OEM. I think people just expect the car to be 1 second faster to 60 and it's just not going to happen. An intake is important if you are modifying the car, though, as you don't want the stock intake to be the bottleneck