i try to shift at 6500 it feels great there but my qt mile mph say differant. i have a 4.88 pro gear that is free so i thought about running a 29" slick with it but i would like to run a 28 . im dont want to spend the money on a 4.56 if it dont help but i might if i find one soon. i have zero intention on running nos. just a all motor truck.. thanks