Ok My brother has a 1986 chevy truck reg cab short box 2wd. We just swaped a 2003 5.3 liter in it. The mods are air intake, exhaust, no cats, program, and electric fans. He has a 3000 stall and he is running this through a th350 trans and 4.10 ratio posi rear. The truck weighs 4025 with him in it. Ok my truck is a 2003 gmc sierra excab Z71 with 5.3 long tubes, electric fans,pulley,no cats cutouts and program. My truck weighs in at 5020 with me in it. I have 3.73 gears and no stall, I launch in 4hi. We need to know what is happening because we are dead even in a race from 15mph to 90 then @90-115 I can pull him by about 1-2 lengths. This doesn't make since because the 1000 lbs I out weigh him by. Please chime in, Can my extra mods do that much or does the th350 suck. Let me know, Thanks, Jared

 

Maybe it's the 410's limiting him on the top end? Maybe even aerodynamics? You also have longtubes and cutouts, while he has the stock manifolds and through the muffler. Got any pics of your brother's truck? Sounds like a pretty nice setup.