when NOS is used, there is an acceleration, hence G forces are
felt. otherwise, when u're travelling at 200km/h, u won't feel
anything if u're travelling in a straight line. but when u're
driving at 200km/h and make a turn, there is lateral acceleration,
so u feel the "cornering forces". when a helicopter makes a turn, u
will feel the forces acting on your body as well.
one thing tho, a car is much nearer to the ground, hence stationary
objects whizzing by provides a sense of speed, even tho the body is
physically experiencing no force at zero accelertion, while in a
heli up in the sky, there are no near objects to provide the visual
sensation of speed.