This is what my '85 Mustang with the 408 ran @ 4200' Density altitude.
Naturally aspirated, hydraulic cam, granny-shifted World Class T-5 on 8.5" slicks.
The 14 second pass belongs to my Pontiac TransAm Buddy who's just slapped on the spray! His times will dramatically improve when the track opens back up!
As for my Cobra, the previous owner says that he cut a 12.0 @ 120 on Drag Radials and skinnies, so hopefully it will stay in the 12's in Amarillo.