Cusco, you came across as a wind-up on your first post. Perhaps that's why nobody took you serious. Call me stupid but I now believe you really have never seen a pressure-activated stall warner. They're common on Cessnas, and the DA-40 has 'em too.
It's nothing more than a hole in the leading edge of the wing, just below the line where the air normally separates itself into a low pressure area above the wing, and a high pressure area below the wing. In other words, in normal flight, there is a high pressure (higher than static, I mean) pushing into the hole. Nothing happens in this case.
As you approach the stall, the line between low and high pressure shifts downward due to the higher angle of attack. The hole is now in the low pressure area (lower than static), and air is sucked out of the hole.
The hole is connected, via a tube, to a sort of whistle in the cockpit, which makes a loud buzz as soon as air is sucked out through it. That's why you french-kiss it as part of your preflight checks: by sucking on it, you should hear the buzz. And yes, that is yuck, so there are little harmonica-like things for sale that do the sucking for you.
The advantage over a vane-type like in the PA-28 or Robin is that this system requires no electrics with all the problems associated with that (like mentioned in this thread). The disadvantage is that sometimes insects fly (or even nest) inside the hole, and it's harder to prevent them from icing over compared to electric vanes.