I've noticed that too. Tough it's not so strange, the dv outlet has a diameter of 25mm? Ur intercooler is mostly 62mm? So you close the throttle, dv opens, but diameter is much smaller, thus creating pressure buildup, meanwhile there is no exhaustgas to propel the turbo. So your turbo will stall. Driving without a dv will obviously create even more lag.
A dv is nevertheless very usefull to minimise stalling
ofcourse ALS (antilagsystem) will sort stalling, but pretty expensive and won't last that long, so more rebuilds needed. But, gives some good bangs


i've heard about a guy who had 2 dv's installed, but i don't know if that really sorted the stalling