My kaplan progression --->
diagnostic: 498
FL 1: 500
FL 2: 505
FL 3: 507
FL 4: 505 (woops, a little too much going on the night before i suppose)
FL 5: 508
P/S I would second what everyone has said about KA and also say just continue to practice passages to get a feel for them. Since they are essentially always some sort of experiment get used to identify demographics, IV, DV etc... Anything they might ask about. Also focus on really understanding the figures, IMO if you understand the figures and exp. design it is pretty easy to crush these passages given requisite content knowledge.
As for score projection, I am not sure how or why but it does seem that you get a 10 pt boost +/- 5 pts... A buddy of mine finished kaplan with a 511 on FL 5 and ended up hitting 523 on the real thing.
Edit: baseline target of 510, but hoping to match or exceed performance on the scored AAMC FL, my dream would be 515-520 range