I have a superchip for my duramax but really i wouldn't recomend it. it has 3 setting and the higher you go in power the better fuel you get. the problem with that is on the top level for my truck it adds about 120hp more and the tranny is said to only take 90-85hp more.
i have a problem with shifting but i thinks it's due to the fact that i have the 6 speed allison. i tried on my dads 5 speed allison (like the one in the h1 alpha) and it shifted great. go to
www.dieselplace.com those guys will answer all your questions