My old car slowed down considerably with a cowl hood. A switch back to six pack scoop and the performance was restored. Was kind of amazed, but can't really fight the numbers. Must have been somekind of an aerodynamical gremlin. I have yet to see a six pack or Hemi scoop that doesn't work, but the openings are huge and create a lot of lift, and propably don't help the drag coefficience either. You don't have any scoop limitations, so I would propably bick a modern style, reasonably high pro style front facing scoop.