I had a set of the AEM Tr-Power Pulleys installed on my Prelude, and I have to say there was a significant inprovement in power (butt dyno). If you go to the link they have a disclaimer which reads:

*IMPORTANT:
Vehicle manufacturers have thoroughly investigated the use of torsional vibration dampeners and conclude that their use significantly reduces NVH (noise, vibration and harshness). Furthermore, manufacturer and independent research shows that torsional vibration dampeners are critical to engine life where long-term use is intended. Removing the torsional vibration dampener from an engine can be highly detrimental to its long-term operation!