There is no doubt in my mind that it does increase the sound of the turbo spooling.
I never owned the MSP without the Injen intake, the turbo was always noticeable but I wouldn't say it was loud (from inside of the car). After redoing the exhaust from the downpipe back I would go as far as saying that it screams (in comparison to stock)
Well Whoever had my car before me had done stuff to it like put boost control and took the air box out and put a Perrin air filter. So I can hear the spool and the bypass. But it's not all that loud outside the car as it is inside.