When my shop put the Perrin dp on my car it was for a manual tranny and I have a 5eat. The result was the pipe touched the firewall and sounded identical to yours.
I would bet your dp is rubbing your frame somewhere and transmitting all the sound into the cabin.
Mine went almost as quiet as stock when they put a properly fitting invidia dp on.
Oh and btw, your turbo could explode and kill all furry animals within a 100 meter radius.