When I first got my Duster, I had this big ugly scoop on it:
When I installed a Moroso air pan to seal the carb to the scoop, the car went faster.
When I switched to a six-pack style scoop without an air pan, the car went faster.
When I recently removed the 1" carb spacer and installed a Hilborn style scoop (under the six-pack scoop), the car went faster (picked up in the 60'):
My neighbor had a Camaro, he had a forward-facing scoop and switched to a cowl scoop. The car ran almost exactly the same number, so he switched back to the forward facing scoop as the cowl hood was too big.