Going to order a tune from Nelsons soon. Its for an 01 2500hd 6.0L 4x4 with a rebuilt 4L80e. Just some quick questions? Anyone had a tune in this type of vehicle and what gains did you see? I dd it and tow as well so going with the 87-89tune. I would like to remove 100% tm. Cant see why Id need it? And when I stomp on it I want it all! LOL. Does Nelson normally increase the shift firmness for normall driving? The order form is kinda vaque. I would like firmer for normall throttle and harder for Wot and towing etc. Thanks for any tips/Hints or experiance guys. Looking for more Oomph and MPG.