Not sure how,but I have like 3/4 versions of efi on laptop.
one is 7.2-saves as .tun but won't open a .ctz
7.5 won't save as .tun and then there is v8 and another one floating somewhere.
v7.5 is what I read with and use.
Really should have familiarized myself with it first,bought a truck specifically to figure it out but trying to get a driveable tune on this huge cammed truck today/tomorrow.