Fundamentally, the tunes are for performance and also "optimum" settings based on airflow.
The slip ons and the Full systems both fundamentally change air flow in the bike and this new air flow has to be compensated with the fuel ratios.
I've been meaning to ask some Ducati Experts out there, if the ECU is constant mapping the A/F ratio based on the exhaust gases, then should it not accommodate for the new exhausts as well?
So, the Tune, if done, should do the fine tuning, but without the tune, it may not have the highest level of performance but its not damaging to run without the tune right?
I've heard that the Akra slips ons don't need a tune, but some places it mentions that you do.
Akra will only give you the map once with the original purchase and its done with the service dealers only, so if you're DIYing it, not sure how you get it done.