I did mine a slightly different way. I took a clear piece of rigid plastic and marked the four holes from the drip tray that will bolt through to the heat extractors. I cut the four holes out and then layed them over the heat extractors with the studs sticking through the four holes in the plastic. I traced onto the plastic where the two vents were and cut them out. This became my template for cutting the hood. I took the insulation off the bottom of the stock hood and then held the drip tray against it. It fits over the support braces of the bottom of the hood fairly snug so you can only put it in one place. I marked the same 4 holes again from the drip tray onto the bottom of the hood and drilled them through. Now take the plastic template you made and lay it on top of hood lining up the four holes to mark the vent holes. Go ahead and cut the vents out now. The only thing left to do to the stock hood is to drill a few small holes in the underhood braces for the small screws that hold the drip tray.
