I'm running 3.42:1 gears, 4l60e/vette servos, and 4.8L with LTs, CAI, 1.75:1 rockers, and hypercrap 93 octane tune with trans pressure boosted. I don't think there is much of a weight difference between the OBS RCSB truck and my 2002.
I ran a 15.3 lately without the tune or the rockers. No telling what i run nowadays. I also have terrible reaction times, like .4s is the fastest i've gotten