I have had to change vin numbers in the past between me and a couple guys and try different tunes. Since it is recommended to flash tune then read it and change bidirectional function to new vin. How can my buddy and I run the same base tune and tweak indiviually if I can not read the file from the ecm. It is ok to just use the bidirectional funtion with out loading it on a vehicle first. I really want to learn more about the functioning of the capabilities of the tuning but need some guidance on many things if I can not figure them out. Thanks anybody.