For RACORs run 30 mic if you have relatively dirty fuel or 10mic if you have relatively clean.
Note that the on-engine "last chance" is a 7 micron and is on the pressure side. It is also a bit small in terms of size, which means with a 30mic primary you can plug it FIRST, which is not too cool when you're underway and it's 150 degrees in the engine room, since changing that one is somewhat of a pain in the butt.