[ian332isport]

I get that you need to keep the data files updated to keep pace with anything the dealers may do to your car, but at what point do you need to update the version of ISTA (D or +) ?

Do you need to keep updating the ISTA version to be able to use later data files ?

[RocketSurgeon]

Each version of ISTA can only use data from the same version, otherwise you get a data mismatch error. You can't update ISTA like Esys PSDZ, you need to update the whole program. You can run into problems working on cars with newer i-step than your version of ISTA contains. Diagnostics would probably work as long as the model is covered by your version, but coding or flashing would be prohibited.