Ok, lets say you were running 1 Bar of boost. When air is compressed and travelling through the intercooler and then through the trottle body into the engine, what air pressure would be lost before it gets into the engine? Probably a differece if you either use a bar-and-plate or tube-and-fin intercooler, am i right? Then as you get your foot off the accelerator and the throttle shuts, the air is forced backward towards the compressor, again loosing pressure when having to travel back again through the intercooler and back to the compressor wheel......
Now if you know the end result of pressure effecting the comressor wheel, wouldnt that be the factor of how much damage could be done to the wheel, bearings, etc?
Does this make sense?...lol (correct me if i am wrong)
Just my 2 cents.
Steve.