Standard&Poor's Ratings Services has assigned its 'AA' rating to Portage, Mich.'s downtown development, limited-tax GO capital improvement bonds, series 2003. At the same time, Standard&Poor's has raised its rating to 'AA' or its 'AA' underlying rating (SPUR) from 'AA-' on Portage, Mich.'s outstanding bonds. The upgrade reflects the city's growing tax base that has gradually decreased its reliance on one, major taxpayer. The upgrade also reflects the implementation of managerial practices that helped weather financial pressures without adversely affecting the general fund balance. The rating also reflects the city's: Participation in the Kalamazoo-Battle Creek MSA; Above-average wealth and income levels, combined with below-average unemployment levels; Sound financial reserve levels; and Moderate debt levels. Considerable tax base