Chameleon_CLK

So recently i've upgraded my supercharger pulley for a smaller one and gotten a pretty decent power increment, getting it up to 225hp and 325Nm from the stock 190hp and 280Nm, but i now have a question... The seller of the pulley told me that with a smaller pulley i would build more boost, which makes sense, but when i asked him if i needed to reprogram the air flap in the air box of the car so that it would open at 0.8 bar of pressure instead of the stock 0.5, he told that it wasn't needed... I found that curious and decided to install an air pressure gauge to test out that theory, and to my surprise, when i did, i found out that it was still making 0.5bar of pressure... But this leaves me wondering, if the car is making the same amount of boost, how is it that i've gotten an increase in power? Im definitly not a mechanic but i do find this hobby of mine extremely interesting and wanted to learn more how the air flap actually works, which for some reason, the seller refuses to explain.
Can anyone help me out? How is the car making more power with the same boost? How does the air flap work? Is it possible to reprogram it? I have lots of questions...