; (B) as the Administrator considers appropriate, incorporate changes based on such comments into the final revision of the Handbook; and (C) provide a response to all significant comments. (e) Interim implementation of changes (1) In general Except as provided in paragraph (2), not later than 1 year after the date of enactment of this Act, the Administrator shall issue program guidance letters to provide for the interim implementation of amendments made by this Act to the Airport Improvement Program. (2) Alaska exceptions Not later than 60 days after the date on which the Administrator identified reasonable exceptions under subsection (b), the Administrator, in consultation with the Regional Administrator of the FAA Alaskan Region, shall issue program guidance letters to provide for the interim application of such exceptions. 734. GAO audit of airport financial reporting program (a) Audit Not later than 18 months after the date of enactment of this Act, the Comptroller General shall initiate an audit of the airport financial reporting program of the FAA and provide recommendations to the Administrator on improvements to such program. (b) Requirements In conducting the audit required under subsection (a), the Comptroller General shall, at a minimum— (1) review relevant FAA guidance to airports, including the version of Advisory Circular 150/5100–19, titled Operating and Financial Summary , that is in effect on the date of enactment of this Act; (2) evaluate the information requested or required by the Administrator from airports for completeness and usefulness by the FAA and the public; (3) assess the costs associated with collecting, reporting, and maintaining such information for airports and the FAA; (4) determine if such information provided is— (A) updated on a regular basis to make such information useful; and (B) audited and verified in an appropriate manner