Caltracks VS Super Stock Springs

With your s/s springs 002,003 is there any tricks done to them to get that low of 60 foots. I have a 3000 lb duster with me in it and just the backs are clamped. I run 580 horse small block 416 and the best i can get is 1.47
best time to date [email protected] opinion. I due have a trans brake but i dont use it because it hits the tires to hard and i run a slower 60 foot. any ideas?