I just had my pulley installed and cost me $525 total including labor. One thing with the Dinan pulley is that the belt is so tight that it took my mechanic hours to get it to fit. Almost thought Dinan sent the wrong belt because it was almost 1/2 inch short but he finally managed to get it in. I do feel a slight difference and thought it was worth the money. Dinan said the pulley was a healthy upgrade without risking any damages to the motor. Pulley was $305 on
https://getbmwparts.com because of the 20% off deal which ends this month. If it wasn't for the sale I would've went with the Macht Schnell or Turners.