Wrong. ALL 2006 and 2007 GT's were supercharged.

In 2006 the GT became the base, the GTP became the GT. You could still get a loaded "base" but it was going to have the NA engine.

Go to any website where you have to enter info about your car and if you put in that you have a 2006 or 2007 Grand Prix GT it brings up that you have the supercharged 3.8.