The Tial wastegates are designed to leak. The leak you heard is normal. This has been covered over and over again. Tial has even posted a YouTube video of it because so many people were talking about it (especially on the Honda forums).
When I first obtained my tial 38 mvs the first thing I did was to try to test it like an IWG by applying pressure to it with a MityVac in order to observe and ensure that the valve was opening as expected. It didn't. I heard pressure leaking away. Why? Because the tial EWG is not designed to hold pressure applied. It is designed to leak off that pressure through the valve stem. After simple research this all became clear.