1. How much would this take off of my 1/4 mile?

2. How hard is it to install?

BTW: I have a 2004 2500HD with the 6.0L

 

i don't think it will take ne thing off of your 1/4 time. they are not hard to install, it comes with a video, watch it a couple of times and pay attention carefully and i think you will be fine.

 

use the video for reference only
Itll have you taking apart things that doesnt need to be
make sure to follow the book
it was the hardest thing Ive done to my truck yet
but Ive never been past the filter on any transmission
helped put a few in but never went inside 1
its the only thing Ive done to my truck that Im not
100% sure everything is right
hell Ive still got springs washers gold rings and crap laying around
just make sure you take your time