Back when my duster was going 12.00's I cut the steel hood and installed a bolt on 6 pack scoop. I didn't make a pan to seal the carb to the scoop but it didn't seem to make real big ET difference. (might of picked up a few hundredths at most). The only difference I noticed was the car did seem to run just a tad cooler. I ended up making more changes in the weeks after that so I didn't have many weeks of the same combo to make a comparison to.