Kinjo, my heavy as hell 92 extended cab runs 9.51 in the eight and with the 1.56 factor to calculate the 1/4 shows 14.83 but I bet it runs quicker than that. My engine is all stock LS1 parts at this time. The truck even has heavy cast aluminum Eagle wheels with 32x10.5x15 tires, also heavy. The heavy tonneau cover and subwoofer box with 2 10" Stillwaters is a good 60 lbs more. How much heavier is an extended cab anyway? About 300 lbs?