Section 906 Certifications - --------------------------- I, Charles E. Porter, a principal financial officer of the Funds listed on Attachment A, certify that, to my knowledge: 1. The form N-CSR of the Funds listed on Attachment A for the period ended July 31, 2003 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and 2. The information contained in the Form N-CSR of the Funds listed on Attachment A for the period ended July 31, 2003 fairly presents, in all material respects, the financial condition and results of operations of the Funds listed on Attachment A. /s/Charles E. Porter Date: September 25, 2003 - ---------------------- ------------------------ Charles E. Porter, Principal Financial Officer Section 906 Certifications - --------------------------- I, Karnig H. Durgarian, the principal executive officer of the Funds listed on Attachment A, certify that, to my knowledge: 1. The form N-CSR of the Funds listed on Attachment A for the period ended July 31, 2003 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and 2. The information contained in the Form N-CSR of the Funds listed on Attachment A for the period ended July 31, 2003 fairly presents, in all material respects, the financial condition and results of operations of the Funds listed on Attachment A. /s/Karnig H. Durgarian Date: September 23, 2003 - ---------------------- ------------------------ Karnig H. Durgarian, Principal Executive Officer Section 906 Certifications - --------------------------- I, Steven D. Krichmar, a principal financial officer of the Funds listed on Attachment A, certify that, to my knowledge: 1. The form N-CSR of the Funds listed on Attachment A for the period ended July 31, 2003 fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and 2. The information contained in the Form N-CSR of the Funds listed on Attachment A for the period ended July 31, 2003 fairly presents, in all material respects, the financial condition and results of operations of the Funds listed on Attachment A. /s/Steven D. Krichmar Date: September 24, 2003 - ---------------------- ------------------------ Steven D. Krichmar, Principal Financial Officer Attachment A - -------------- 003 Putnam Investors Fund 007 Putnam Voyager Fund 073 Putnam Premier Income Trust 035 Putnam Tax-Free Insured Fund 2AQ Putnam Research Fund 2SL Putnam International Fund 2000 2AP Putnam Growth Opportunities Fund 036 Putnam Tax-Free High Yield Fund 001 The George Putnam Fund of Boston 006 Putnam Vista Fund 024 Putnam OTC & Emerging Growth Fund