When Mainani and Ngalinn are in boom states, you can quickly grind Imp rank flying back and forth with data missions. I did that in one day AFAIR. Fed rank has been nerfed, but fly to any station being repaired and look at the missions. They need certain stuff to rebuild the station (can't remember which). Go to a station nearby selling those goods, and then visit the stations being repaired. Then you can pick supply missions and hand in the goods (without leaving the station since they're already in your cargo), and thereby rank up quickly.That makes no sense to me ... they are both rank locked.
Edit: Use a large ship with plenty of cargo space and some serious guns, since you will have to argue with pirates along the way.