First of all, vehicles for the vehicle achievement, which are missing or have a really low drop rate like the longspur in foundry or maehlstrom jail ( i was run that about 100 time and i didn´t see it). Maybe you can make a quest, if you have run the fp in one week 5 times you can get the vehicle.
Second, also increase the chance to get vehicles from ops, like denova, that minimum one vehicle drops every run.
Third, like mentioned before, by the opeventboss eyeless the chance to get the symbiont rakghul is 10%( or less) in every run. For example: If you run with 8 people and everyone wants the rakghul, you maybe must run 80 times. That is unfair and not possible in one week. Please change it