You're definately leaking. If you have a mechanical boost gauge with a thin nylon hose make sure tat s not kinked up or a hole in it as well cause if it gets cracked it will show 0 vacumn and still show boost just not full boost.You'll figure it out. if you are not idling bad then it can't be a real lage leak.

Oh and it is common for the t25 to loose boost a about 5k rpm. It should not ccompletely loose it though.