Hmmm I think I am experiencing a similar problem... On recently I have noticed that when I put my foot down and the car starts to boost it used to just lauch so to speak, now I can hear what appears to be extra large sucking sounds for a short period then the power jumps in. I don't know if I am being paranoid or not but my boost guage ( standard in dash ) doesnt really seem to begoing as high either..
Is it possible I have a hole in a hose or popped a pipe off or something simple???