OIRA operates largely in secret, exempt from most requests under the Freedom of Information Act. It routinely declines to release the changes it has proposed, the evidence it has relied upon to make them, or the identities and affiliations of White House advisers and other agencies' staff it has consulted. OIRA doesn't even disclose the names and credentials of its employees other than its two most senior officials. Maybe that's why you've never heard of OIRA.