i have an 06 4x4 2500 cummins and aginst my better judgement i installed a used predato on my truck last week to test before i bought it but i ended up not liking it the problem im having is before i installed my speedo was reading under do to 35's and now it is reading about 5mph over and i did go back to orginal parameters one more thing i did adjust tire size with programmer any help would be appreciated thanks