Dap
What you have is more in line with what I am considering-how tall is it? How far back does it extend past the back of the hood? I see this as the biggest problem with a cowl on a Duster as there is nearly 8" between the back of the hood and windshield.

It seems like the folks that are seeing good results have them close to the windshield, but I am unsure if they seal them or not. I am also still curious if there is some science to how far above the carbs the scoop is.

Just so we keep this interesting, I have considered taking a short cowl scoop and turning it around so the the opening is very near the front of the hood, as to get the "good air", kinda like the aero style super stock scoops that get the opening low and very near the front of the car.