To the person who asked me if I've ever done this (sorry, I should check the original post). No I've never done this, no I don't think there's any real big harm here. But you do want to properly set the wastegate at your target boost. I assume that since your car has the two stage boost setup, you've got an intercooler and thus the wastegate actuator and overboost switch that can handle being set at higher boost pressure.

I suppose you do run a few risks, such as not setting the boost properly (and ending up with either no boost or enough to overwhelm the fuel system). However, it should be otherwise harmless. I seem to remember hearing that Volvo initially used this to avoid compressor stall. However, I doubt this is an issue on an otherwise 240.

From badbricks (typos and all):

To Big
......At low rpm the turbo is sluggish and at the higher rpm the turbo flows more air than the motor can handle. This causes the turbo to start "surging" or superheating the compressed air. This can also cause turbo stall. (Turbo stall is when the boost starts backing up all the way back to the compressor housing, slowing the compressor wheel down, thus creating much more back pressure on the exhaust side of the turbo; this big bad chain reaction will lead to the early death of the turbo and possibly the engine as well)

- alex

'85 244 Turbo