My friend has a 2001 silverado 2500hd ex/lb with a 6in lift 37inch mud grapplers. He also has a stock trans with 180k on it n a efi live tune thats suppose to put 425hp to the rear wheels. Yesterday he was in stop an go traffic for about an hour n realized his trans temp got to 250 degrees. When he went to accelerate and merge onto the highway the tranny slipped really bad. the trans got near 300 degrees . He let it cool for an hour and it drove home. Today he has drove it n its been fine but i know its about to go. Why would the tranny get so hot it even in traffic it just doesn't seem right?