shift kits

Anybody ever install a shift kit in a 2500HD with the 6.0? I wanted to know how much they cost and if it was worth it. I'm thinking instead of a pcm tune I may just install this for added low end torque. Would this help or be a waste of time?

http://www.transmissionpartsusa.com/4L80E_HD2_Performance_Reprogramming_Kit_p/500-046930hd2.htm

I have not a 4L80E but this is a nice kit and will help the 4L80E live a longer life.

//2000CAYukon