Multimode polymer waveguides constitute a promising technology for use in board-level optical interconnects. However, the continuous improvements in high-speed performance of VCSELs raise important questions about their ability to support such high data rates due to their inherent highly-multimoded nature. Thorough experimental studies on the bandwidth of a 1.4 m long multimode spiral waveguide are presented in this paper, indicating a bandwidth-length product of at least 35 GHz×m even in the case of an overfilled launch. No significant transmission impairments are observed for spatial input offsets, while error-free (BER<10⁻¹²) data transmission over the 1.4 m long spiral waveguide is demonstrated at 25 Gb/s.