I have a 2008 silverado v-max. I have hp tune on it now, I think the guy who installed it doesn't know what he's doing. The truck is still sluggish. And my buddy's 5.3 crew cab smokes me. I know it's not right because I use to have a 2001 lightning bolt on mods . I tuned it my self. All of the tm is turned off . On the motor and trans. Any help would be great.