Instantly reduced my 1/8 mile time by .1 second when I added the 4.10s. 2800 stall reduced it another .1. My best was 9.23 with my 92 C1500 Xcab with a tuned stock 98 LS1. I actually started out running 10.2s with 32x10.5x15s. I lowered the truck 4/6, added 4.10s, played some with the tune, got some almost slick tires to race with. Lots of practice got my times faster and faster. A good cold air intake that has a ram air effect helps, too.