I have a 2004 GTO with the P59 computer. It currently has a 2 BAR OS. If I want to change to a 3 BAR OS, would I have to first Write Entire the stock OS file, then Write Entire the 3 BAR OS file?
Or would I simply take my stock OS file, apply the 3 BAR OS modification, save the file with a new name and Write Entire from 2 BAR OS to 3 BAR OS?