Stk6 I'll give you my 2 cents worth. If its doing this while your on the gas then its probably a compressor map surge area your in, if its doing it when you let off its normal. I haven't read about hardly any ta49 owners talking about that turbo having surge problems and its a very popular turbo. I had a te44 w/ a V4 IC and you could certainly hear it surging between about 7 and 14psi but, as quick said, if you pushed past that boost level everything was fine and it would clear up and really start pulling good. You could see about changing your IC configuration as that will effect this noise/feel depending on what you currently have.
HTH