Two friends each with 2000 base model Preludes. Both had AEM CAI, stock header, exhaust, and a VAFC. One had AEM pullies and the other didn't, that was the only difference in the cars. They dynoed back to back. Car 1 (no pullies) made 174.6whp and 140wtq. Car 2 (with pullies) made 174.8whp and 141wtq.

The peak numbers are more or less identical. The difference could have been due to the straps on the dyno, tire pressure, etc. I wish I still had the dyno plots ... the curves were identical. In other words, pullies don't do anything. Others may have a different opinion, but I've seen the evidence first hand.