[turbocarrera]

Are you guys talking about a CIS pop-off valve or a turbo blow-off valve? The pop-off is for NA CIS airbox protection in the event of a backfire. The blow-off valve is to vent boost from the intake when you quickly let off the throttle. This creates a backpressure wave which can damage a turbo, and create lag the next time you get on it. BOV's do not control boost pressure or spikes in boost pressure - the wastegate does that.