From what I was told the extractor vents are for aerodynamics. Along the lines of the vents in both the tail and the spoiler, which if I remember correctly Peter said were ineffective. Maybe if Peter sees this post he will chime in.
#5104K 351W sportsman block,408.AFR 185 heads, Tremec 3550, stack system with Electromotive Tec3 system. IRS,.Sold,
Coupe delivered.Dart 427 stroker with weber carbs.AFR 205 heads. Irs and willwood brakes all around.