Originally Posted by Modshack

All you actually have to do is remove the gasket that seals the hood to the firewall area. Air naturally flows into that pressure area (why the HVAC intakes are there) and will provide ventilation to the engine compartment. This may prove more cosmetically acceptable to the "Z" crowd looking to achieve temp reductions. I have done Temperature datalogging on my old Audi TT with and without the gasket and found an 18 dgree reduction in engine bay temps. Noise increases a bit as one of the primary purposes of the seal is to control NVH. The concept here is sound, the way to achieve the benefits can differ..

Graph shows the difference between the sealing gasket on and removed over a short road course, with a period of idling at the end on an 80 degree day...