The Version3's of the boss Navis give different versions of their Chips depending on how well you fare against them. But normally the highest Chip you can get is their V3. In order to pickup their V4 you must be in the Team Style, and defeat them with an S Rating within 20 seconds.

Or the ezier way (i got most of their V4 by this method)
If you have a lot of BugFrags, take the random chance of earning their V4 there, the BugFrag machine is found in Secret Net 3 where you fight Bass GS.