From Whalesalad:
"Air goes into the intake. It goes back behind your motor, by the firewall, and down into the turbo. Turbo blows that air through your intercooler (also known as a charge air cooler) where it becomes "charged". At that point the air is cooler and more compressed, which is what helps create more power in your engine.
Right before this wonderful and magical air is about to enter your throttle body and later into your engine, there is a big Y pipe. One side of that Y pipe goes right into your throttle body, and then the cylinders. The other side of the Y pipe leads up and around the side (left looking from the front, on the passenger side) of your engine, up and back to your firewall where it ends in a little dongle that makes noise."
The noisepipe is unnecessary added volume to the charged side of your turbo system.
Whalesalad:
Don't mean to be dumb here but everyone talks about better throttle response when removing the noise pipe. From your explanation, since there is less 'dead space' are we really talking about less turbo lag as the turbo will spool up more quickly?
Is turbo lag the same as throttle response? And is turbo lag less with the noise pipe delete?