Energy Savings Performance Contracts Amendments Act of 2003 - Amends the National Energy Conservation Policy Act (NECPA) to: (1) repeal the termination dates governing the authority to enter into energy savings performance contracts (thus extending such authority indefinitely); (2) allow as an approved benefit ancillary to an energy savings contract or energy savings performance contract providing for energy savings through construction of replacement facilities those savings resulting from reduced operation and maintenance costs at such facilities; and (3) authorize the Secretary of Defense and the heads of other interested Federal agencies to enter into a pilot program for energy savings performance contract investments in non-building energy efficiency improvement projects.