Extra precise measuring tape, coupled with an extra large sharpie to give a good 6mm grey area of where the line actually is. In retrospect tape wouldve helped
Used a drill to relief each corner then went through with an angle grinder for all the horizontal cuts.
Each vent is 7.25" wide and roughly 1" tall, a sheet of semi-rigid plastic was lain in to act as a duct.
I realize all the air in the world at the front of a radiator does nothing if pressure in the engine bay keeps flow from happening but this is part of the process. Better flow through the bumper with ducting, then hood ventilation and more heat mitigating material for wiring/hoses. Currently the hood is too hot to touch, while driving the hot air moving under the car and through the trans tunnel heats the interior by at least 25°F.