Its called twincharging:
http://www.speed.org.nz/garage/levin_gtz_twin_charging.phtml http://www.geocities.com/MotorCity/Lane/1231/twincharging.html Interesting enough, but doesn't seem to have many advantages over a good turbo setup. (see above articles.)
Here its used on a airplane engine:
http://www.mecanair.ch/frame.htm Good luck implementing that on a contour!
