Originally Posted by pbonsalb
No. They slow down accessories or they would not add any power. I think AA is saying its pulley does not slow down accessories like the water pump quite as much in order to maintain coolant flow and therefore does not make quite as much power.
I think the difference is negligible. Macht Schnell claims gains of 9-14hp and AA claims 12+ hp. Both claim factory harmonics stay in tact. Only differential I see would be price and AA has a $50 off sale right now.