My wife's company has been in the machining business since WWII. Every machinist like mechanics have an opinion. My point is staying within safe parameters. Like what MB AMG did when designing and yes, machining the stock pulley. A pulley can be machined to a 65 or a 62 with the same safe guards, or thickness, if you will, as the stock pulley. That is my only point. If you had yours done by a good machinist who kept it true...then I am sure it will last you a long time. Mine will be doing hard launches all next yr week in, week out. I will go for the safe guards...Plus, I want to keep the stock pulleys for future use. These parts aren't going to be around forever...