Well actually on a "percentage" basis I don't think theres "that many" replica Cobras that run under 12, fewer still in the 10's.
Many of them COULD, most often there just not set up for it, with traction being the primary issue. Cobras were never about the "1/4" mile, they were about road racing, and even today with their old design they still do very well indeed at what they were designed for.
I didn't do anything special to mine to run the 1/4, just run what I brung. Full tire pressure all around, air cleaners on, 92 octane with street timing and a soft launch (2 sec 60ft). But I DID remove the side pipes. 11.904 at 121mph I would consider that pretty darn "fast" for a replica.
Anthony, point WELL taken about the Vettes!