I had a 67 barracuda coupe with a 440.I used the 67 bigblock A body manifolds.The car would run 14.40 in the 1/4.I switched to fenderwell headers,fattened her up a tad and went 12.60s.I couldnt believe the difference.This was with the .484 mp hyd cam,2500 converter,850 holly dp.,and a 3.90 rear gear.