I just sold my Hypertech to my boss for his 02 2500HD D/A. After installing it truck ran great. The next day he noticed that his truck did not start as quickly as usual. He has not put it back to stock yet to see if it is the truck or the hypertech doing it. Have you ever heard of a duramax starting slowly? It is not anything bad yet but snow is coming and it cant let him down then. He is taking it in for warnanty soon if it does not get better. Thought you might now the problem. Thanks....