I believe that only possible way to detect it is with 4/250 ....
As I used "Volhnov" with wide and narrow beam (as it's transmitters are the most powerful available into the SIM, and didn't saw it at this range, so my conclusions are that it is more "stealthy" than F-117... Maybe when it drops bombs it's RCS is much bigger, but don't know is it simulated or not (probably not)... Anyway I am interested about RCS of B-2 in the SIM...