The point im trying to get across is that there is the potentual we all have different mods and boost levels and it isnt somthing we need to consider before removing the bov. Turbosmart link - The pressure within the intercooler piping continues to increase until the compressor reaches its pressure limit. When it reaches this limit, it cannot flow the air any more and the built up air pressure inside the intercooler and pipe begins to flow backwards through the compressor which is trying to flow air forwards. The result of this reversal flow of air is the immediate deceleration of the turbocharger and a high load on the bearings which support the compressor/turbine shaft. At low turbo speeds and low pressures, the deceleration of the turbo and the load on the bearings is low, I.e. a small amount of fluttering at low engine speeds and throttle movements is negligible. At high turbo speeds and high pressures, compressor surge during a gear change can be damaging to the bearings of the turbocharger as the deceleration rate of the turbocharger is high and the reversal airflow through the compressor is high