i did a computer swap on a 2000 silverado. we went from the old 4 plug style computer to a newer 2 plug style on the 4.3l. we have a problem where the tach reads lower than it should be reading. the reading in hpt scanner seems to be right but the dash is wrong. what can i do to fix this? does he need to go to the dealer and have the dash cluster recal'd for the newer computer?