So I recently purchased a Nuk5 from Baby Pants. It's in good condition, but one thing I did not expect is how slow the nipple reinflates while sucking on it. I've read in forum posts and online reviews that the Nuk5 sometimes makes a whistling or wheezing noise while sucking on it - which mine does. Both of these issues seem to be related to how air flows in and out of the nipple.
So here's my question - Is this intended? I don't have to wait long for the nipple to reinflate (less than a second), but it was something I immediately noticed upon switching to the Nuk5 after using Nuk3's. I've heard about people poking holes or modifying the pacifier in some way to increase air flow, but I'm interested in knowing if someone has owned a Nuk5 that didn't have this problem.
I'm mostly curious about whether this is intentional, or simply a very common design flaw (though I hesitate to call it a flaw if it is indeed intended and perhaps even favorable to many).