Spot on. Stock engine were tested under close environment, the stock filter box was designated to isolate hot air and able to match stock ECU fuel mapping. Lower restriction of air filter does not necessarily mean POWER LOSS. However, under certain range of RPM, low restriction filter yield much better torque+power output than stock paper filter.

So it's true, under certain driving condition, BUTT DYNO did feel the right thing. For example when I'm using open pod,  the car has a clear improvement on 3~5krpm range. Especially when you're driving at trunk road, infront is low speed vehicle around 70kph, you're in 4th gear 2.5krpm. You've decided to overtake, so you dropped to 3rd gear @ 4krpm, with a low restriction filter in place, as soon as you kick on the gas pedal you'll have the feeling of getting hit by a 30tons truck from behind kinda accelaration. Whereas, on stock paper filter you wouldn't get that, even on 3rd gear @ 4krpm, you'll still feel the car unable to overtake in time then dropped to 2nd gear, 6krpm @ 70kph. But then as soon as you engaged 2nd gear @ 6krpm, you realized you're very closed to the rev limiter and hesitated wouldn't know whether you can overtake the car infront safely

Meanwhile, a drop in kinda low restriction filter posses the goodness of maintaining cool air intake function, as well as air buffering just like the stock paper filter. Other than high RPM range might result in LEAN(due to more air than ECU preset low fuel consumption settings), drop in filter makes much balance improvement on mid RPM than openpod.