LOL, just go argue with all the people who done it with their Mazda3, I've done it and i see that the engine respond quicker on low RPM, and I do more KM/Litres. You should see how big is the Intake resonator on a Mazda5 (bigger than the Mazda3) and you will understand imediatly !
Sorry... I wasn't trying to argue or anything. Personally, I think I'll just wait until someone can show me a dyno chart with a proven increase.

Actually when talking about airboxes, the bigger the better...in most cases.