For those who are interested in the current max score, this note from NWEA states that the maximum valid scores (across the whole grade range) are 350 or 320, depending on which battery is administered. (Range from 100-350.) Scores above the maximum can be recorded, but will be invalidated by the system. The 2015 norms document, referenced there, also notes that the 99th %ile for 11th grade is 285 for math, and about 260 for reading and language, which suggests that scores above those ranges are unlikely to add meaningful normative information.
ETA: Oh, and the 99th percentile in math for the algebra II end-of-course exam is 291.
https://community.nwea.org/docs/DOC-1651MAP K-2 (aka MPG) also has hard RIT ceilings of 230 for math, and 220 for reading.
https://community.nwea.org/docs/DOC-1496
